The Hand-Me-Down PC
Motherboards, Memory, CPUs - Upgrading Old PCs
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The Hand-Me-Down PCMotherboards, Memory, CPUs - Upgrading Old PCs |
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This book has been replaced in most usages by my latest book:
PC Repair with Diagnostic Flowcharts. Click here to get there:-) Copyright 2005, 1996 by Morris RosenthalIn the first two sections of the book, we talked about what components make up a PC, and how the software sets the lower limits on the type and configuration of the parts you need. Most buyers of a hand- me-down PC will know the CPU type, how much memory is installed, and the size of the hard drive. Some lucky readers will receive all of the original documentation that shipped with the computer, but even then, the documentation will cover a whole range of models and configurations. Free PCs will often come with no more information than an off-hand, "I think it had three something." In all of these instances, there are four ways to learn about what's really in the system box: 1) Inspection of the ports on the back of the PC, and the exposed drives on the front. 2) Reading the system configuration displayed at boot (power on) time 3) Running a software reporting application, like MSD (Microsoft Diagnostics) 4) Taking the cover off the system box and looking inside Visual Inspection of the System BoxThe easiest thing to determine, looking at the front of the system box, is whether or not you have a CD drive. A headphone jack, volume dial, large doorway and the "Compact disc" trademark, combine to make a dead giveaway. You can also determine whether the drive requires a CD caddy (into which the CD is placed before being inserted into the drive), or if it is a permanent tray type. The caddy type will have a doorway that pulls down or folds inward, while a tray will be visible edge on, as an immovable cutout. If you see you're bringing home a caddy type, make sure you get at least one caddy with it. You can also see the floppy drives from the outside of the system box, and whether or not you have both sizes, 3 1/2" and 5 1/4", but you can't be sure that they are the newer high density types until you boot the machine and format a floppy. Systems less than 5 years old will almost certainly have the newer type. The back of the system box provides much more information. Two telephone jacks, located in the same slot (you will see eight slots separated by thin metal strips), indicate the presence of an internal modem. The rest of the ports, which are shaped like thin trapezoids, can be identified by the sex of the receptacle, and the number of gold plated pins or pin holes you count. The port that your VGA or SVGA monitor is attached to, is a female port with fifteen pin holes Very expensive cards for big monitors may have five BNC connectors (like on the back of your VCR) instead, but these are rare. Four more ports will should be included in all modern PCs: a 9 pin male connector (Com1), a 25 pin hole female connector (Com2), a 25 pin male connector (LPT1), and a 15 pin hole female connector (Game). These ports may be located in the slots area, or they might a little closer to the power supply fan. Occasionally they are labeled, but rarely. A sound card can also be easily identified by several audio jack inputs, for the microphone, speakers, and direct line input, a volume dial, and often, a 15 pin hole female feature connector. Some systems will include other ports, for SCSI cables, scanners, video inputs, etc. Don't bother guessing at what these ports are until you boot the PC and see what software installs. Some SCSI adapters use the same 25 pin male adapter that is used for the printer ports, and some systems include an extra printer port. If you have more than one 25 pin male port on the back of the PC, don't plug in external SCSI devices or printers until you open the system box and determine which port belongs to which adapter. A printer plugged into a SCSI port can damage the printer, the SCSI adapters, and any internal SCSI drives attached. System Configuration Displayed at BootMost systems built since the late eighties will display a "System Configuration" screen when the PC is turned on or rebooted (reset). This is the BIOS (Basic Input Output System) reporting what parts it sees in the computer. System configuration screens appear differently, depending on the BIOS manufacturer, but the following information should always be included:
The System Configuration report is the best way to learn about the system, because the BIOS that generates it is also operating the computer. If you believe a component has been reported by the BIOS incorrectly, one of two things is wrong. First, a hardware option could be set wrong, by a jumper in the system box or a software configuration program, and the BIOS is correctly reporting what it sees. Second, an option like floppy drive type could be set incorrectly in the CMOS setup, and can be corrected by hitting the "Delete" key, when prompted during boot, and changing the setting. The BIOS has no way of actually determining whether or not a floppy drive really the type that is entered in the CMOS setup, and a wrong drive type will result in read and write errors. Software Reporting ApplicationThere are many software utilities for sale that can help you determine what hardware components are in the system box and what their performance is. The most popular of the is the Norton Utilities, which includes tools for data recovery and other housekeeping tasks. However, you can get almost as much information for free, providing you have Windows 3.1 or a recent version of DOS installed. Just type MSD at the DOS prompt, and the Microsoft Diagnostics program will start. Microsoft Diagnostics reports on the following items:
Looking in the System BoxBefore a hardware upgrade takes place, somebody has to open up the system box. For individuals doing their own work, this is a step that should be taken before buying any hardware. For those who will pay someone else to do the work, make sure a technician looks at your system before you walk out of the shop. Most upgrades are dependent on your motherboard and the other adapters and drives already installed. In some rare cases, even with the system box open and the adapter card in hand, neither you nor an experienced technician will be able to determine what the adapter does. These are usually external tape controllers, or interface adapters to industrial equipment, and are especially common in PCs that have been sold to company employees. Opening up the system box (removing the skin or cover) will be the easiest step of the process with 75% of the PCs, and the hardest part for the remaining 25%. There are three basic variations used to attach the cover for desktops and minitowers, all of which occasionally involve removing the plastic faceplate or a plastic back facade first. Safe Handling of Computer Components Computer components are shipped in space-age anti-static bags, to protect them from the 15,000 to 50,000 Volts of electricity that our bodies can store up in static electricity. The first rule for working on PCs is to avoid rooms where you get zapped every time you touch a doorknob or other metal object. The next rule is to leave the PC plugged in when you are working on it, since the third wire in the cord provides true earth ground. This is only true, of course, if you have the computer plugged into a legitimate three prong grounded outlet. You should always power a PC from a a grounded outlet, and not use a "cheater" that converts the plug to two prongs. The ground not only helps protect against static discharge, it also helps protects your home from electrical fires cause by a short circuit, and reduces RF (Radio Frequency) interference with devices like your portable phone or TV. Before you open a static proof bag to handle a part, touch the metal casing of your PC to ground yourself, discharging any static charge you have picked up. Make sure you have enough lighting at your work space before you begin. Do not walk across the carpet with the part in your hand to examine the part under a lamp. If you put the part down, without installing it in the computer, put it back in its bag. You can generate static electricity by flipping through a large instruction manual, so remember to touch the case before you pick up the part again. Never touch the gold or silver contacts on the bottom edge of an adapter, because the oil from your fingers can create an insulating layer and degrade electrical signals. In spite of all these warnings, computer components are pretty robust on the whole. I have handled tens of thousands of components over the years, and to the best of my knowledge, only once did I damage a part (a SCSI hard drive) with a static discharge, which I clearly I felt when it occurred. 1) Removing a Three Sided Cover.The three sided cover is the most common type used for minitowers, and is also used for a good number of desktops. The only difference between the cover as used in minitowers and desktops is the desktop has a broad top and short sides, while the minitower has a narrow top and long sides. The cover, which appears to end flush with the plastic faceplate of either type of case, actually has tabs that extend under the edges of the faceplate, to secure the cover in the front. The screws that actually hold the cover on are usually located along the edges of the back of the case, normally four or six in number, though occasionally three or five are used on some desktops. These are not the four screws grouped around the fan, they hold the power supply in place! In some instances, there will be no screws in the back, but two screws at the bottom of each side of the cover. Remember to take note of how the cover comes off (slide back and lift, tilt and lift, etc..) because it will have to go back on the same way. 2) Removing a Faceplate Attached CoverSome system boxes, primarily desktops, are built with the plastic faceplate permanently attached to the three sides of the cover. These covers are attached either with screws at the bottoms of the sides, around the edges of the back, or occasionally by one large-knobbed screw in top center of the back. In all instances, once the screw(s) are removed, the cover and the faceplate will slide forward a couple inches, and then be lifted off. Some brand name computers use two thumb activated slide locks on the front of the case to secure it, and no screws at all. These covers often require a strong tug to get moving, because the fit between the drive faceplates (floppies, CD, tape) and the cover faceplate is tight, and the cover faceplate has to move while the drives remain where they are. Floppies are pretty rugged, and if their small plastic faceplates pop off, they can be easily replaced, but try and be gentle if you have a CD drive. 3) Removing a Back Attached CoverThese are the rarest of the cover types, and are most often accompanied by our fourth variation, which requires prior removal of the faceplate. The screws may be located on the front of the system box, and only exposed once the face plate is removed. Once the attachment screws are removed, the cover will slide back a few inches, then be lifted off. Unfortunately, this method of attachment often forces you to unplug all of the devices from their ports to get the cover off (keyboard, monitor, mouse, etc..) 4) Removing a Plastic Faceplate or Back FacadeSome manufacturers, particularly makers of towers, like to hide all of the screws beneath a plastic facade. This leaves no exposed screw heads on the outside of the case. More frequently, there is no back facade, but the only screw heads showing are the four holding the power supply in place. There are two methods for holding faceplates and facades onto a system box, the first is snap-together plastic fasteners and the second is Velcro. Velcro is most often used on back facades, and can be easily detected because the facade can be jiggled a little, the attachment isn't rigid. Cover your ears and rip away. The snap on faceplates and facades are somtimes a little nerve racking to remove. A sharp tug at the bottom of the faceplate is the best place to start. Similar to faceplate attached covers, the biggest problem is the fit between the faceplate and the fronts of the exposed drives. There are normally four-snap together connectors on these faceplates, one at each corner, though towers may employ six. The male part of the connector can be close to an inch long, so the faceplate needs to be pried out quite a ways before it releases. By this point in the book, you should know what parts are in the PC you own (or are considering buying), and know what upgrades are necessary to run the software you want to use. Now we will examine the costs and labor involved in performing the upgrades you need. Even if you intend to pay somebody to make a house call, or to bring your PC to a shop, you should read the sections describing the labor involved. For each procedure, we will not only give detailed instructions, but also a time range for how long the upgrade should take. Most of these upgrades will take less than a half hour, and many take just a few minutes. But, if you are paying somebody to do the work, be prepared to pay a minimum hour labor charge regardless. Whenever you plan to open the system box of an older PC for the first time, you should write the hard drive parameters recorded in the CMOS settings (see motherboard upgrades) before proceeding. Memory UpgradesThe most common, and the easiest upgrade to make, is adding more RAM to a system. The price of memory fell more than 70% in 1996 and 1997, meaning that the 16MB that cost $500 for Christmas 1995 cost less than $150 for Christmas 1996, and is under $50 for Christmas 1997. Before you buy additional memory, or pay for an upgrade, somebody must determine not only how much memory you have, but what kind it is. Also, memory cannot be added in arbitrary amounts, but in fixed increments that depend on the type of CPU you have. If the system was built before 1994, it will use 30 pin SIMMs (Single Inline Memory Module). Otherwise, unless you have the original documentation, you will have to look inside the system box and determine what size of memory SIMM you have. In all cases, if you have the motherboard documentation, read the section on adding memory. It may have details about SIMM type and grouping not covered in the following sections. Single Inline Memory Modules (SIMMs)A SIMM consists of several memory chips (jargon for encapsulated integrated circuits) mounted on a small circuit board, which in turn is placed into a socket on the motherboard and held in place by spring loaded clips. There are two different physical sizes of SIMMs, which are described by the number of contacts between the SIMM and the socket. Section four contains a discussion of the interface between the CPU and memory that explains SIMM sizing. Some very old 386s and older computers were not equipped with SIMMs, and in no circumstance is it worthwhile to upgrade the memory in these PCs. All 386s that use SIMMs, along with older 486s, will use 30 pin SIMMs, which have 30 contact points, and are also known as "eight bit SIMMs." Starting with newer 486s, 72 pin SIMMs were introduced, which are also known as "thirty-two bit SIMMs." These two types of SIMMs appear physically different in three ways. The 30 pin SIMMs are three inches long, have a straight bottom edge, and have 30 gold or silver contact points along the bottom. The 72 pin SIMMs are 25% longer than 30 pin SIMMs, have a notch in the middle of the bottom edge, and have 72 contact points on the bottom edge. After determining what type of SIMMs your system uses, you will want to count how many free (open) SIMM sockets there are on the motherboard for you to add new SIMMs. During the transitional period between 30 pin and 72 pin SIMMs in 1994 - 1995, some companies manufactured motherboards with both types of SIMM sockets, which is easy to spot since the 72 pin sockets are 25% longer. You will also want to count how many SIMMs are installed, so by comparing the number to your total amount of memory, you can determine their size in megabytes. Two more details can help prevent problems occurring after the upgrade is completed. With the system power off, remove one of the SIMMs from its socket by gently pushing in the clips securing it with your thumbs, or a screwdriver if necessary, and wiggling the SIMM to see which direction it will release. Then, holding the SIMM by it's edges, count the number of chips. SIMMs with an odd number of chips are "parity" SIMMs, and upgrade SIMMs of the same type should be purchased. Also, examine the chips for a number following a dash, like "-100", "-80", "-70" or "- 60". This is the speed of the memory chips in nanoseconds (billionths of a second), and the lower the number, the faster they are. SIMMs added during an upgrade should be the same speed or faster. SIMMs are organized on the motherboard into sets called "banks". Older PCs, like 286s and 386SXs, use a bank size of two, meaning SIMMs are installed in multiples of two. All 486s and 386DXs utalizing 30 pin SIMMs use a bank size of four. A 486 with 72 pin SIMMs has a bank size of one, while a Pentium or 586 has a bank size of two. Finally, SIMMs have different capacities, depending on the chips mounted on them. For 30 pin SIMMs, three standard sizes were used: 256K (four SIMMs to make 1MB), 1MB and 4MB. For 72 pin SIMMs, the three sizes you are likely to encounter are: 4MB, 8MB and 16MB. Using bank size as a guide, we will now go through the upgrade possibilities for each CPU type. The new DIMMs, which came on the market in 1996 and are the standard memory module in new Pentium PCs, are 64bits wide, meaning the bank size for a Pentium is one DIMM. Time and Cost for UpgradesIn 95% of hand-me-down PCs, upgrading the memory should take less than five minutes. There are two exceptions, one not quite as irritating as the next. The first exception is if the SIMM sockets are located under something that is removable, like the power supply, or a detachable drive bay. In this case, it takes a few extra minutes to get the part out of the way, and to replace it after the upgrade. The really annoying situation comes when the SIMM sockets are located under a welded piece of the case structure. This requires you to remove the motherboard in order to have at the memory, turning a simple upgrade into a half hour to an hour job. The cost of generic memory SIMMs is now less than $5 per megabyte, with the price dropping slightly as the size, in megabytes, of the SIMM rises. Some brand name machines may use proprietary SIMM modules, different from the industry standard parts we have mentioned. Aftermarket replacements for these modules are widely available through mail order, so you can at least learn their prices before going to a store. Adding Memory to a 286 or 386SXThe motherboards for these systems have either four or eight SIMM sockets, with a bank size of two. We will consider each case based on the amount of memory already installed in the system. Since larger capacity SIMMs are cheaper per megabyte than smaller capacity SIMMs, buy two 4MB SIMMs for the price of six 1MB SIMMs, and end up with more memory. We won't consider every mathematical possibility for adding SIMMs, just those up to 8MB, and then a jump to 16MB. Always install newer SIMMs, that have a higher capacity in megabytes than the existing SIMMs, in the lowest bank number (usually bank 0), and move any older SIMMs you are keeping to the higher banks. If you already have 6MB or 8MB installed, don't walk into a shop and ask for an upgrade to 16MB. Tell them you want to add 8MB, and you will end up with either 14MB or 16MB, depending on the type of SIMMs already installed, and save about $100. If the SIMMs installed in your system have nine chips mounted on them, use SIMMs with nine chips for the upgrade. If the SIMMs in your system have an odd number of chips on them, purchase parity SIMMs for upgrades. 1MB installed (286 and 386SX)This means that there are four 256K SIMMs in your system. We aren't going to consider adding 256K SIMMs (a waste of money), so the smallest upgrade you can make is to add two 1MB SIMMs, bringing your total memory to 3MB. If your motherboard only has four total SIMM sockets (none available), you must remove one of the banks of existing SIMMs before adding the two new 1MB SIMMs for a new total of 2.5MB. To add 4MB, you must add four 1MB SIMMs (a single 4MB SIMM doesn't make the required bank size of two). If the system has eight SIMM sockets, you can simply add the four 1MB SIMMs for a new total of 5MB. For systems with just 4 SIMM sockets, you will have to take out all of the old memory, for a new total of 4MB. To get to 8MB, you have two choices. Remove all 256K SIMMs, and add eight 1MB SIMMs, or just add two 4MB SIMMs (cheaper, too). The only way to get to 16MB is to add four 4MB SIMMs. 2MB installed (286 and 386 SX)Either you have eight 256K SIMMs installed (so take four out and follow the 1MB installed example), or you have two 1MB SIMMs installed. Adding two 1MB SIMMs gets you to 4MB, or adding two 4MB SIMMs gets you to 10MB. If you have eight SIMM sockets, you can add more memory in two SIMM increments without taking the two 1MB SIMMs out, otherwise the only way to get to 16MBs to fill all four SIMM sockets with 4MB SIMMs. 4MB installed (286 and 386 SX)You have four 1MB SIMMs installed. If you have eight SIMM sockets, you can add more memory in two SIMM increments to get to 6MB, 8MB, 10MB,14MB or 20MB. If you only have four SIMM sockets, You will have to give up two megabytes to add two 4MB SIMMs and bring the total to 10MBs. If you want to get to 16MB with just four sockets, you must remove all four 1MB SIMMs installed, and add four 4MB SIMMs. 6MB installed(286 and 386SX)You have six 1MB SIMMs installed. You can add two 1MB SIMMs to get to 8MB total, or add two 4MB SIMMs to get to 14MB total. You can remove two of the existing 1MB SIMMs to add four 4MB SIMMs and get to 20MBs, but it's rarely worth the expense. 8MB installed(286 and 386SX)You have either eight 1MB SIMMs installed, or two 4MB SIMMs. If you have eight 1MB SIMMs, take two out, add two 4MB SIMMs, and settle for 14MB. If you have two 4MB SIMMs installed, add two 4MB SIMMs to get to 16MB. Adding Memory to a 486 or 386DX with 30 pin SIMMsThe motherboards for these systems have either eight, twelve, or sixteen SIMM sockets, with a bank size of four. We will consider each instance based on the amount of memory already installed in the system. Since larger capacity SIMMs are cheaper per megabyte than smaller capacity SIMMs, buy four 4MB SIMMs for the price of twelve 1MB SIMMs, and end up with more memory. We won't consider every mathematical possibility for adding SIMMs, just those up to 8MB, and then a jump to 16MB. Always install newer SIMMs, that have a higher capacity in megabytes than the existing SIMMs, in the lowest bank number (usually bank 0), and move any older SIMMs you are keeping to the higher banks. If you already have 4MB, don't walk into a shop and ask for an upgrade to 16MB. Tell them you want to add 16MB, and you will end up with 20MB for the same price. If the SIMMs installed in your system have nine chips mounted on them, use SIMMs with nine chips for the upgrade. If the SIMMs in your system have an odd number of chips on them, purchase parity SIMMs for upgrades. 2MB Installed (386DX and 486s with 30 pin SIMMs)Although rare, this means you have eight 256K SIMMs installed for a total of 2MB. With a normal eight SIMM socket motherboard, you will want to take out four 256K SIMMs and add four 1MB SIMMs to reach 5MB, or add four 4MB SIMMs to get to 17MB. The only remaining option is to ditch all eight 256K SIMMs, and put in eight 1MB SIMMs for a total of 8MB. If you have one of the equally rare motherboards that have more than eight SIMM slots, you can add four 1MB SIMMs to get to 6MB, four 4MB SIMMs, to get to 18MB, or eight 1MB SIMMs (on the sixteen SIMM socket motherboard) to get to 10MB. 4MB Installed (386DX and 486s with 30 pin SIMMs)On a normal motherboard with eight SIMM sockets, this means you have four 1MB SIMMs installed. The only two reasonable options are to add four 4MB SIMMs for a total of 20MB, or to add four 1MB SIMMs for a total of 8MB. Once, I actually had a 486DX-25 with sixteen 256K SIMMs installed for a total of 4MB! If you are in this situation, you can remove four 256K SIMMs and add four 4MB SIMMs for a total of 19MB, or add four 1MB SIMMs for a total of 7MB. 6MB Installed (386DX and 486s with 30 pin SIMMs)This requires a motherboard with twelve or more SIMM sockets, employing four 1MB SIMMs and eight 256K SIMMs. If there are sixteen sockets on the motherboard, you can add four 4MB SIMMs for a total of 22MB, or four 1MB SIMMs for 10MB total. Otherwise, remove four 256K SIMMs and add four 4MB SIMMs for a total of 21 MB or four 1MB SIMMs for a total of 9MB. 8MB Installed (386DX and 486s with 30 pin SIMMs)You have eight 1MB SIMMs installed. With a normal eight SIMM socket motherboard, the only upgrade option is to take four 1MB SIMMs out, and replace them with four 4MB SIMMs, for a total of 20MB. On a motherboard with more than eight SIMM sockets, add four 4MB SIMMs to get to 24MB, or on a sixteen SIMM socket motherboard, you can add eight 1MB SIMMs to get to 16MB. 12 MB Installed (386DX and 486s with 30 pin SIMMs)You have twelve 1MB SIMMs installed. If the motherboard has 16 SIMM sockets, add four 1MB SIMMs to reach 16MB. Otherwise, remove four 1MB SIMMs, and add four 4MB SIMMs to reach 24MB. Adding Memory to a 486 with 30 pin and 72 pin SIMMsThe motherboards for these systems have four 30 pin SIMM sockets, and two or four 72 pin SIMM sockets. The bank size for the 30 pin SIMMs is four, so if 30 pin SIMMs are used, all four sockets must be filled. The bank size for the 72 pin SIMMs is one, so single SIMMs can be added. We will consider each case based on the amount of memory already installed in the system. We won't consider every mathematical possibility for adding SIMMs, just those up to 8MB, and then a jump to 16MB. If you already have 4MB, don't walk into a shop and ask for an upgrade to 16MB. Tell them you want to add 16MB, and you will end up with 20MB for the same price. If the SIMMs in your system have an odd number of chips on them, purchase parity SIMMs for upgrades. For double-sided 72 pin SIMMs, count the number of chips on one side, to determine for parity if the number is odd. 4MB Installed (486 with 30 pin and 72 pin SIMMs)You have either four 1MB, 30 pin SIMMs, or one 4MB, 72 pin SIMM. The only reason to use 30 pin SIMMs at this point, is if you can obtain them for less than the 72 pin SIMMs. If you can get four 4MB 30 pin SIMMs for free, or cheaper than a single 16MB, 72 pin SIMM, go ahead and use them for a total of 20MB (16MB if you have to remove four 1MB SIMMs to put them in). Otherwise, you can add a single 4MB 72pin SIMM, for a total of 8MB, or two of these for a total of 12MB. You can get one 16MB SIMM for the price of three 4MB SIMMs, so if you are shooting for 16MB, just add a 16MB SIMM and end up with 20MB. Don't use 8MB SIMMs unless one is already installed (support varies). 8MB Installed (486 with 30 pin and 72 pin SIMMs)You have either four 1MB 30 pin SIMMs and one 4MB 72 pin SIMM, two 4MB 72 pin SIMMs, or one 8MB SIMM. In either case, to get to 16MB, add either two 4MB 72 pin SIMMs, or one 8MB 72 pin SIMM, if an 8MB SIMM was already used. Adding Memory to a 486 with 72 pin SIMMsThe motherboards for these systems have four 72 pin SIMM sockets. The bank size for the 72 pin SIMMs is one, so single SIMMs can be added. We will consider each case based on the amount of memory already installed in the system. We won't consider every mathematical possibility for adding SIMMs, just those up to 8MB, and then a jump to 16MB. If you already have 4MB, don't walk into a shop and ask for an upgrade to 16MB. Tell them you want to add one 16MB SIMM, and you will end up with 20MB for the same price. If the SIMMs in your system have an odd number of chips on them, purchase parity SIMMs for upgrades. For double-sided SIMMs, count the number of chips on one side, to determine for parity if the number is odd. 4MB Installed (486 with 72 pin SIMMs)You have one 4MB SIMM installed. Add one 4MB SIMM to get to 8MB, or add one 16MB SIMM to get to 20MB. Don't try 8MB SIMMs unless you have documentation confirming they will work. 8MB Installed (486 with 72 pin SIMMs)You have two 4MB SIMMs installed, or one 8MB SIMM. Add two 4MB SIMMs to get to 16 MB, or add one 16MB SIMM to get to 24MB. If you have one 8MB SIMM installed, add one 8MB SIMM to get to 16MB. Adding Memory to a PentiumThe motherboards for these systems have four or eight 72 pin SIMM sockets. The bank size is two, so two SIMMs at a time must be added. We will consider each case based on the amount of memory already installed in the system. We won't consider every mathematical possibility for adding SIMMs, just those to go from 8MB to 16MB. If you go to a shop, ask for 8MB to be added. If the SIMMs in your system have an odd number of chips on them, purchase parity SIMMs for upgrades. For double-sided SIMMs, count the number of chips on one side, to determine for parity if the number is odd. The new DIMMs, which came on the market in 1996 and are the standard memory module in new Pentium PCs, are 64bits wide, meaning the bank size for a Pentium is one DIMM. 8MB Installed (Pentium)You have two 4MB SIMMs installed. Add two 4MB SIMMs to reach 16MB or add one 16MB SIMM to reach 24MB. If you have documentation that the motherboard supports 8MB SIMMs, you can add two 8MB SIMMs for a total of 24MB. For an illustrated guide, see how to replace RAM. Video Adapter UpgradesThe main reason for upgrading a video adapter is to increase the number of simultaneous colors that can be displayed. Another reason is to get the maximum performance out of a new monitor. Finally, you may want a high performance video adapter that displays screens faster, or includes MPEG hardware decoding for displaying real motion video. Many older systems that were equipped with motherboards sporting VLB (VESA Local Bus) slots were shipped with ISA (Industry Standard Architecture) adapters (see section four on motherboard bus slots for more information). Now that a 1MB VLB video adapter costs the same as a ISA 1MB video adapter, you may as well buy the VLB adapter if you are upgrading. If you already have an SVGA adapter, but cannot display more than 256 colors in VGA mode or 16 colors in SVGA mode, you should investigate if adding memory to the adapter is an option. Time and Cost for UpgradesIn 100% of hand-me-down PCs, replacing the video adapter should take less than five minutes. However, installing the new video drivers for both DOS and Windows can take up to a half hour, if several floppies comes with the adapter. It's a rare PC shop that will properly configure the adapter for the monitor. This involves checking the monitor manual for the scan frequencies it supports, and setting the proper mode with a program included on the utility disk that comes with the video adapter. The install software that come with the video adapter will copy the program that invokes the mode to your CONFIG.SYS or AUTOEXEC.BAT files (see section four for details on startup files), but the mode setting program will use low performance defaults until somebody changes them. Some brand name machines will have the video adapter integrated with the motherboard (not a separate adapter). To upgrade these systems, you will definitely need the manual, unless you can find the jumper that disables the VGA on the motherboard so you can add an adapter. New SVGA cards with 1MB of memory cost about $50, and I recommend clones using Trident or Cirrus Logic chips. You can pay a lot more for brand names with more memory and higher scan rates, and it becomes a matter of reading reviews and comparison shopping. The $50 adapters are more than enough for all but professional CAD or Desktop Publishing users with $500+ monitors, or serious game players. Upgrading Video Memory on an Existing AdapterSometimes a SVGA video adapter is installed with less than its full complement of video memory, which would enable it to display more colors and higher screen resolutions. This can only be determined by looking at the original documentation that came with the adapter, or taking it out of the system box and looking for empty memory sockets. These sockets usually have the type of memory chip required for an upgrade printed right on the circuit board, but if not, you will have to contact the manufacturer for the correct chip to use. Systems with SVGA integrated on the motherboard may also support more memory, but you will need the motherboard manual to figure it out. Installing a New SVGA AdapterThe first step, before removing the old adapter, is to start Windows, double click on the "Main" icon, double click on the "Windows Setup" icon, select "Options" and "Change System Settings" then go to the "Display" list. Scroll up or down until you find "VGA" with nothing else, and select it. The next time you start Windows, you will have the default 16 colors VGA driver that works with every adapter manufactured. If you forget to do this, and the software that comes with the new SVGA adapter isn't smart enough to change the Windows settings for you, you will have to run the Windows Setup program from DOS. You do this by changing to the Windows directory and typing "setup." Then you can change the "Display" type to "VGA" and re-run the adapter installation software. Next, remove the old VGA adapter, and insert the new video adapter in a bus slot. If the new adapter is a VLB adapter, and the CPU speed is some multiple of 40MHz (ex. 486DX-40, 486DX2-80, 486DX4-120), you will also have to find and set a timing compatibility jumper on the motherboard, The jumper is usually located between the VESA bus slots, and is selectable for less than or equal to 33MHz or >33MHz. For CPUs that are a multiple of 40MHz, or the rare 486DX-50 (not the 486DX2-50), you will change this jumper to >33MHz. The only other issue is making sure the adapter is seated well in the bus slot, which is split into two sections. The ISA section near the back of the PC, and the VESA section near the CPU. The screw that holds the adapter in place will help seat the ISA section of the adapter, but make sure the VESA section, which is farthest from the screw, doesn't pop out when the screw is tightened. Also, if you already have one ore more VESA adapters in the system, make sure you can fit a VESA video adapter before purchasing one. Although motherboards usually feature three VESA bus slots, CPU cooling fans and bad motherboard layout sometimes physically prevent more then one of them being used by all but the shortest VESA adapters. The next step is installing the software that comes on floppy disk with the adapter, which can require up to three steps, for those using DOS and Windows application programs. 1) Install the utilities, which include a program that needs to be informed of the monitor specifications, to take advantage of non-interlaced monitors and high scan rates. Most utilities will allows you to try all of the display modes your monitor supports with a test pattern, a good way to see if you're getting what you expected. The utilities install program may include a VESA compatibility driver for DOS software. 2) Install the DOS software, for each DOS application you are using. This lets older DOS versions of popular applications utilize some of the same screen presentation features as the Windows version. If the only DOS software you use is DOS itself, or games, you can skip this step. Most DOS games have a setup option of their own, which supports the popular video adapters. Some games will support the VESA extension (same organization that created the VLB standard, different extension), a software driver that existed as an alternative to Windows for providing a standard interface between video adapters and software. VESA drivers are no longer included with all video adapters. If you know you will need one for a specific game or other some DOS software, ask this question specifically before buying the adapter, and make sure they don't think you're talking about VESA local bus drivers. 3) Install the Windows software. Read the instructions carefully, as some install programs need to be executed in rather bizarre manners (the old Trident 9000s from one manufacturer were installed correctly by typing "README" on the A: drive). Some older install programs will require that you have your Windows disks on hand, others will supply all of the files required. When installed properly, you should have a new icon in Windows for the video adapter that, lets you change screen resolution and the number of colors diplayed at one time. Selecting new settings is carried out by point and click, but remember that the software will always need to restart Windows before the changes take effect. If you find yourself using Windows "Setup" to control the adapter, you've probably installed the driver software wrong, and should have another look at the instructions. For an illustrated guide, see how to replace a video card. CPU UpgradesOne of the most sensible upgrades to make is replacing a slower, first generation Pentium CPU with a faster MMX part. CPU upgrades should never be attempted unless you have the original documentation for the motherboard, and then you should stick with upgrade processors supported by the documentation. The WWW sites of the CPU manufacturers (Intel, AMD, etc..) have great documentation on compatibility information, and FAQs about installation. One note on the Intel site explicitly states "Intel does not recommend upgrading 50-MHz or 66-MHz Intel 486 DX2 processor based systems with a DX4 Overdrive Processor." Fast 486 AMD and Cyrix processors are incredibly cheap, but all those currently being manufactured by AMD are 3.3V and 3.45V parts, which will not work on old motherboards that only supported 5V processors. Cyrix does manufacture a series of clock doubling and tripling 5V CPUs that will work in many older motherboards. There are aftermarket parts which allow you to use upgrade CPUs with some otherwise incompatible motherboards, but they aren't cost effective. Time and Cost for UpgradesIf you have the motherboard documentation, and it lists an upgrade processor, the actual installation, takes about five minutes. In most cases you will have to re-arrange some motherboard jumpers for the upgrade processor, but the most challenging pert is normally getting the old CPU out of the socket. Newer motherboards all come with ZIF (Zero Insertion Force) sockets, that use a lever to lock the CPU in place. With these sockets, the only trick is to put the new chip in with the correct orientation. On older motherboards, the CPUs were simply pressed into the socket, and you will want to pry it out very gently, so you can reuse it, in case the upgrade doesn't work. Upgrade processor prices start around $50 for some of the AMD CPUs, to several hundred dollars for Intel Overdrive Pentium parts. Do not bring a PC to a computer store for a upgrade processor unless you have the original documentation, or you purchased the system from that store. Most stores will attempt an upgrade without documentation, and problems will begin to appear only after the PC is used for hours, or days. Most upgrade processors will require a heatsink and fan (for dissipating the extra heat generated at the higher operating speed), so make sure to order one, if it isn't included in the kit. Reasons not to Upgrade the CPUIn almost all cases, a new motherboard and CPU will cost the same or less than an upgrade CPU. A new motherboard will also get you a new, updated BIOS, which will bring you "Plug-and-Play" compatibility, along with greater compatibility with newer software. A new motherboard means a new system bus, and a 64bit memory interface to take full advantage of Pentium processors, something upgradeable motherboards don't do (see section four on memory). Most importantly, a new motherboard and CPU will not be anywhere near as problematical as an old motherboard and an upgrade CPU. The only extra factor to consider in purchasing a new motherboard is whether to use your old memory, which I don't recommend unless you have 16MB or more. For an illustrated guide, see how to replace a CPU Motherboard and CPU combination upgradeUpgrading the motherboard is the one way to turn a hand-me-down PC into a brand new computer. The only thing that can prevent you from doing a motherboard upgrade is if you have a non-standard case. Unfortunately, many brand name systems do have non-standard cases, either slim desktops, or completely proprietary designs. If you have the original documentation, and it states that the old motherboard is a "standard AT" or "ISA" form factor, then you're OK. One problem with some older system box designs, especially Compaqs, is they used a non-standard power supply connector. There is actually a simple, non- expensive solution, for dealing with non-standard cases. Order a new case and power supply with your new motherboard! For this $40 to $70 extra, you really will have a new computer. The only extra work entailed will be transferring over the drives from the old system, which takes a maximum of four screws each. The time lost doing this isn't much longer than the time it would have taken you to get the old motherboard out of the old system. Time and Cost for UpgradesA motherboard upgrade, using an old case or a new case, will take between fifteen minute and an hour, depending on how much experience you have, and whether or not you run into any screws with stripped threads requiring pliers to remove. The cheapest upgrade worth doing includes a new motherboard and a 486DX2-66 or DX2-80 CPU from AMD or Cyrix for about $70. Motherboard/CPU combinations in the 120MHz to 133MHz range, using clock multiplied 486s or 586s (not Pentiums) run around $150 or higher. Motherboards with the Intel Triton Chipset and Pentium processors start around $150 for the P-133, cost around $200 in the middle range (P-133 P-166). The more advanced Pentium MMX, Pentium PRO, and Pentium II CPUs and motherboards start around $250 and go as high as $1000, depending on the particular generation and speed. While upgrading motherboards requires taking out and putting in a lot of screws, it's actually a very uncomplicated job on DOS/Windows PCs, since no software drivers are involved. Windows 95 PCs will usually come up in safe mode when a motherboard is swapped out from underneath them, and can may require some updated drivers. You will have to spend a minute or two in the CMOS setup when the system is first powered up, telling the BIOS what floppy drives are installed, and letting it auto seek the hard drives. Removing the Old MotherboardThere is one step you should take before you actually remove the old motherboard. Power up the system, enter CMOS setup (hit the "Delete" key after the memory count is finished), and enter the first menu item, normally called "Standard CMOS Setup", or something similar to this. Record the numbers for the hard drive(s) parameters on a piece of paper, and note the floppy drive type(s) also. Now, you can shut down the system, and remove the cover. To remove the old motherboard, you will first have to remove all of the adapter cards. Each card is held in place by one screw on the back edge of the case, and is remove by pulling straight up. If an adapter seems stuck, try lifting one end out first. You should never need to pry an adapter out with a tool, though sometimes, you will need to use a bit of force. You can leave any cables running from the adapters to internal drives attached, and pile the adapters gently on top of the power supply. Next you will have to remove any cable attached directly to the motherboard, which is normally limited to the two power supply connectors, P8 and P9, and a bunch of small connectors with thin wires that go to the buttons and LEDs on the front of the system box. If the pins they connect to on the old motherboard are labeled, and the small connectors aren't, you may want to put little pieces of tape on them with TLED (turbo light), TSW (turbo switch), KEY (key lock), PWR (power light, sometimes integral with key lock in a five pin connector), HDD (hard drive light), and RST (reset switch). If you forget, or get confused, you can always follow the wire back to the faceplate and see where it goes. Besides, the only one that's actually useful for anything is the reset switch, and I rarely bother hooking up the others on systems I build for myself. The next step is to find and remove all of the screws holding the old motherboard in, which can number from one and five. These screws are attached to standoffs, tall nuts made of brass or steel, which are themselves screwed into the case. This is the trickiest part of the job, because if the person who screwed in the standoffs didn't tighten them, they will unscrew from the case when you try to remove the screw. This is bad, because most motherboards are also attached to the case with plastic spacers, which need to be slid an inch or so through a slot to be removed, and the protruding standoff will prevent this. One solution is to re- tighten the screw, and hope when you loosen it the next time, the standoff will stay attached to the case. Another other solution is to use some small wire clippers to cut the heads of the protruding plastic spacers, than lift the motherboard right out. If you have a minitower, the screw ends of the standoffs are often exposed on other side of the case, and can be held from turning with pliers while you extract the screw. On some minitowers, the pan (sheet metal) that the motherboard is attached to isn't welded in place, and can itself be removed from the case with just two screws, making the job easier. For an illustrated guide, see how to replace a motherboard Preparing the New MotherboardThere are few things you should do before you screw the new motherboard in place. First, insert the new CPU in its socket, being careful to match the flattened outside corner of the chip with the flattened inside corner of the socket. Open up the manual that comes with the new motherboard, and make sure that all of the jumpers are set right for CPU type (486, AMD 586, Pentium, etc.) and speed (100MHz, 133MHz) etc. Read the table carefully, and make sure that you find the exact CPU that you have. Even if you bought a motherboard with the CPU you wanted already mounted, you will want to double check the jumper settings. Next, jumper the turbo switch permanently on, if this hasn't already been done. If the clock speed is above 33MHz, and the board has VLB slots, check for a bus speed compatibility jumper, and set it according to the manual. Finally, mount the memory SIMMs on the motherboard now, so you won't have to struggle to do it with the motherboard in the case. Installing the New Motherboard in the System BoxThe first step is to carefully note the positions of the existing standoffs screwed into the case. Next, lower the motherboard onto the standoffs, and make sure they all line up with tin ringed holes in the motherboard. If there are any standoffs you can't see (and there are usually one or two), take them out. If you miss an unused standoff and power up the system, it may short the motherboard to the case and ruin it. Next, if there is only one standoff left screwed into the case, compare the tin ringed holes in the motherboard with the threaded holes in the case, and see if you can add one or two standoffs back in. If not, it's no big deal. The plastic spacers you put in next and the adapter cards are more then enough to hold the motherboard firmly in place. Tighten the standoffs with a pair of pliers or a socket end screwdriver. Now, hold the motherboard near the standoffs, and note which holes (they can be tin ringed or not) line up with the slots in the case, then snap in the plastic spacers from the bottom of the motherboard. Take note at this point if the connector block for the power supply leads ends up in an inaccessible place, like under the power supply. If so, you can connect the power supply leads at this point (see below). Before you can start putting any screws in, you must insert the round ends of the plastic spacers through the enlarged holes at the ends of the slots, then slide the motherboard over until the tin ringed holes line up with the standoffs. If you have a very difficult time doing this, try to determine which plastic spacer is causing the problem, and remove it (you can cut it off if you have trouble unsnapping it). This is a pretty common problem, since slots that appear to line up are often a fraction of an inch off. If you have all the plastic spacers well placed in the slots, but the motherboard doesn't want to slide, some of the protruding soldered leads on the bottom of the motherboard are probably stuck on the standoffs. If you can pull up the motherboard a little (don't use a lot of force) right over the location of the problem standoff, you should be able to slide the motherboard into place. If this doesn't work, take the motherboard back out and remove the problem standoff. Once you have the motherboard in place, screw it to the one or more standoffs. The next step is to connect the two motherboard connectors from the power supply, P8 and P9. Arrange the connectors so that the black wires in each connector are adjacent to one another in the center of the connection block. The little plastic ridges on the power supply leads that face the motherboard connector are sometimes too long, and interfere with the connector mating well. Don't hesitate to clip them off. If your new motherboard has the floppy drive and IDE (Intelligent Drive Electronics) hard drive and CD connections on the motherboard, remove these ribbon cables from your old SIDE card, checking as you do so that the red wire in the ribbon is adjacent to the end of the connector labeled with a 1 or 2. Re- connect them to the motherboard, with the red wire adjacent to the 1-2 end of the connector, unless it was done the opposite way on the SIDE card, in which case you want to do it the opposite way on the motherboard. The new motherboard should come with small ribbon cables attached to the port connectors, which are mounted on metal blanks that get attached to the back of the system box the same way as adapters. Connect these ribbon cables to the motherboard with the red wire adjacent to the 1-2 end of the connector. Now you can re-install all of the adapters into the motherboard, leaving out the SIDE adapter if it has been superseded by the motherboard. You can hook up all the little wires to lights and switches if you want to, or just hook up the reset switch. If you have a cooling fan mounted on the new CPU, connect it to a power supply drive lead. If all the power supply drive leads are used, remove one from a drive, insert the fan lead in line, then reconnect the other end to the drive. Last, gently turn the whole system box upside down and tilt from side to side to see if any screws fall out, or roll around under the motherboard. Finally, connect the monitor, keyboard and mouse, and power the PC up. If the system doesn't boot, go to the troubleshooting guide in section four. For an illustrated guide, see how to install a motherboard. The computer should jump into CMOS setup when you turn it on. If it doesn't, hit the reset button, and use the "Delete" key after the memory finishes counting to enter CMOS setup. The first item in every CMOS setup menu is called "standard", "system settings" or something like this. In this menu, you want to set the proper date, time, and the floppy drive type(s). If you remembered to write down the hard drive parameters, you can select "User Defined" for the hard drive type(s), and enter the same parameters. If not, save the settings you have entered (normally with the F10 key), and select "Auto Detect Hard Drive(s)" from the menu. The BIOS will now figure out the parameters for your hard drive(s). There may be several more menu items, with names like "Advanced Setup", "BIOS Setup" and others, but the default settings are probably all fine. You might want to look at each menu, and make sure external cache is turned on, if cache is installed on the motherboard. You shouldn't have to change anything else unless you run into problems later, or add new adapters whose documentation instructs you to make changes. At this point, you should see your old system running, but it should be many times faster. Shut the system down, put the cover back on, and you're done.
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The Hand-Me-Down PC Table of Contents |
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