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Deciding a PC's fate?

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When & What to Upgrade?
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Hard Drive

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How to Install...
Hard drive

Choose Your Memory

So, you decided you want to upgrade. Now you need to figure out what kind of RAM chips your computer has. Does the computer use single inline memory modules (SIMMs) or dual inline memory modules (DIMMs)? If SIMMs, are they 30-bit or 72-bit SIMMs? There are three ways to find out: check your manual, check by e-mail to our technical support team, or pop the computer’s case open and have a look. The first choice requires little explanation, so we’ll focus on the other two.

Memory configurators. You can e-mail our technical support team with the Manufacturer, Make and model of your computer and we will advise you on what kind of memory your system requires.

Open up. The manual and memory configurator are handy if your computer hasn’t been upgraded before. If your computer is reporting a different amount of memory than the manual says the computer shipped with or the memory configurators list as the base configuration, you should pop the case open to check whether there are any open slots for new memory modules.

Before you open your computer’s case, shut down your computer, turn it off, and unplug it. Now you’re ready to open the computer. Determine which screws, if any, you’ll need to remove to slide the cover off. Some computers have no screws; you just pull up on a couple of tabs and slide the cover off. If you’re unsure which screws to remove, consult your computer’s manual.

Once the cover is off, ground yourself by touching the computer’s metal case. Now look for a series of slender 1-inch tall by 4-inch wide circuit boards; they’re probably green with small black chips attached. Usually, the RAM chips are near the central processor (the huge chip with a fan or large block of metal on top of it). If you can’t find the chips, look for four identical empty sockets-on some computers, the factory-installed RAM is soldered onto the motherboard, not in the sockets. If the sockets are empty, it’ll make upgrading a breeze; you’ll just need to check your manual or a memory configurator for the type of RAM to order and then pick the amount you want.

Once you find the memory chips, you can make a list of what you have installed. If there are no empty sockets, don’t worry. You’ll just have to remove some old modules to make way for new, bigger ones. Don’t immediately rip out the old modules, however, because they can tell you a little about what kind to order.

You can tell by the number of pins what type of memory you have. The three major types of memory chips are: 30-pin SIMMs (used with 386-series processors), 72-pin SIMMs (used with 486-series and some Pentium processors), and 168-pin DIMMs. SIMMs can differ not only in terms of pins, but whether they are parity or non-parity SIMMs. You can tell the difference by counting the number of chips on a SIMM. SIMMs with 2, 4, 8, or 16 chips are non-parity SIMMs; those with 3, 6, 9, 12, or 18 chips are parity SIMMs. You don’t want to install parity and non-parity SIMMs in the same PC.

Other Caveats

When selecting SIMMs, you also need to check the access speed and Extended Data Output (EDO) compatibility. Make sure the access speed of the SIMMs or DIMMs you’re buying meets the PC’s minimum requirements by either checking the manual, by e-mail, or the old module. The speed is denoted on each memory chip of a module with the last number in a series of letters and numbers. For example, 4P1024DJ-07 indicates an access speed of 70 nanoseconds (ns).

If you have a Pentium processor, you’ll also need to check your manual or a memory configurator to see whether your computer requires EDO memory chips. If you install non-EDO chips, the computer might not boot up. If it does boot, it will run slower than if you had installed EDO chips.

Place Your Order & Install

Now, you can figure out what size modules you must order. You have two options: You can keep some of the modules and replace others or replace all of them. You’ll have to figure out the math to see what kind of configurations you can have. Just remember that with Pentium processors that use SIMMs, you have to install the SIMMs in pairs (for example, two 16MB SIMMs and two 4MB SIMMs). On the other hand, 386 processors require sets of four 30-pin SIMMs, but can support single 72-pin SIMMs. On 486 and Pentium II processors, you can install single memory modules.

Modules: vertical and slanted for SIMMs, and DIMM for DIMMs. Since you might have to remove old memory chips to replace them with new ones, we’ll explain how to install and remove modules from these sockets. If there aren't already SIMMs in the slots, you can tell whether they're slanted or vertical by looking for the retaining clips. If they're about a quarter-inch behind the socket, the socket is slanted. If the retaining clips are to the immediate right and left of the socket, it's vertical.

Before you remove any RAM chips from their plastic packaging, touch the computer’s case to ground yourself and discharge static electricity.