Today's operating systems and applications are RAM hungry. When software runs out of RAM, Windows starts swapping data to and from your PC's hard disk--a much slower process than fetching it from and writing it to RAM. Adding RAM to your PC is one of the easiest and cheapest ways to boost its performance.
Just a few years ago, 16MB or 32MB of RAM were adequate for most PCs, but you need 64MB or even 128MB these days to get optimum performance with a typical set of Windows 98 applications. Plentiful RAM is even more important if you use Windows 2000 Professional. People who process images, edit video, or perform other graphics-intensive work on their PCs may need up to 384MB of RAM.
Compared to most other upgrade options, installing additional RAM is a bargain. Though prices fluctuate, the pricing trend over the past few years has been downward. At press time, RAM prices hovered at approximately $70 for 64MB, and about $125 for 128MB.
RAM is sold in the form of chips contained on small circuit boards called
memory modules. If your current desktop PC was manufactured in the last three
or four years, it most likely uses 168-pin DIMMs (dual in-line memory modules).
DIMMs vary depending on their capacity (16MB, 32MB, 64MB, and 128MB), the
PC's bus speed, the type of RAM chips they contain, and other factors. You
can usually determine what type of DIMM your PC uses by consulting the PC's
manual or by calling the vendor's technical support line. Most memory vendors
are happy to help (see
Most PCs have three DIMM sockets on their motherboards, and one or two of them are usually free. Adding RAM is as simple as plugging in new DIMMs.
If your PC is more than three or four years old, it probably uses SIMMs (single in-line memory modules). Though the examples of memory modules shown in the photos in the accompanying steps are DIMMs, the process of upgrading SIMMs is similar. The differences are that SIMMs pivot rather than plug into their slots, and they must be installed in pairs.
Most PCs today require a type of memory called PC-100 (100-MHz) SDRAM,
though slightly older systems need PC-66 (66-MHz SDRAM), and somewhat newer
systems depend on PC-133 (133-MHz VC SDRAM). Some brand-new high-performance
systems use a new type of memory known as RDRAM (Rambus DRAM), which currently
costs considerably more than DIMMs. Another new type of memory, known as DDR
(double data rate) SDRAM, is showing up in some high-speed PCs, mainly those
that use AMD processors. To find out more, check out the Web sites for
Memory modules are highly susceptible to damage from static electricity. We strongly advise you to purchase an antistatic wrist strap from your local electronics store--such as Radio Shack--before attempting to upgrade your RAM. And since you must unplug your PC before you begin, you'll need to connect the wrist strap to a ground. One option is to slightly loosen the screw holding the faceplate of an AC outlet and connect the strap to the screw. If you don't use a wrist strap, ground yourself by touching a grounded metal object before removing your new memory modules from their antistatic packaging.
Turn off your PC and unplug the AC power. In Pentium II and III systems, the DIMM sockets are situated just in front of the processor, toward the front of the motherboard as you face the PC (see below, top photograph). Intel's ATX system-board specification states only that the memory slots be placed to the right of the seventh expansion slot. Adjacent to the sockets, you should find labels on the motherboard indicating the sockets' numbers. Insert DIMMs in the lowest-numbered empty sockets first.
Usually, the easiest way to upgrade your RAM is to plug in one or more new modules, adding to what you have. But if sockets are filled with low-capacity DIMMs, you may need to remove them just to clear space. Most DIMMs have clips on either side that you can easily push aside. Once you've disengaged the clips, you usually can pull the DIMMs straight out of the socket. If they seem tightly attached, rock them gently to release them.
DIMMs have two notches that allow them to be inserted in only one way. Press them straight down into the socket, but don't force them. You'll know you've correctly inserted them when the clips on each side of the socket automatically snap into place. If the clips haven't snapped in, you haven't lowered the module far enough into the socket.
Don't put the cover back on your PC until you are sure that everything is working. Plug it in and turn it on. If all is well, the system will automatically recognize the new memory and (usually) show it on the screen.
If your PC refuses to recognize the new RAM, locks up, or won't start at all, first turn it off, unplug it, and check to confirm that the memory modules are firmly seated in their sockets. If seating is fine but the lock-up persists, take out all the memory modules and reinsert them. If you still don't have any luck, the problem may be a defective memory module, though that's rare. To check, call your memory vendor's tech support line.