Memory, or more specifically, Random Access Memory (RAM), is an essential part of the computer. As the name implies, it is used to store data for quick "random" access, meaning that data in any part of the memory can be accessed at any time. Although there are several different kinds of memory such as printer memory and video memory, this page only discusses system memory that resides on the motherboard.

Although more system memory can often be the best upgrade a computer can have, too much memory has been known to slow down computers with older processors. At the time of this writing, 32 megabytes of memory should be enough to run most games and applications.

System memory comes in two different forms: SIMMs and DIMMs. SIMMs are generally used on older motherboards while DIMMs can be installed in newer ones. Some motherboards have slots for both SIMMs and DIMMs, but it is generally a bad idea to mix them because SIMMs are slower and will force the DIMMs to run at the same speed.

If you plan to purchase SIMMs, you should know that some motherboards use multiple memory sockets to function as groups or banks. Banks can be formed from 1, 2, or 4 memory slots. Generally, if your computer has a 386 or early 486 CPU, you probably have 4-slot banks of 30-pin modules. Later model 486 CPUs generally use 1-socket 72-pin modules. Pentium processors need 2-slots of 72-pin modules. Both SIMMs and DIMMs can commonly be found in 8, 16, 32, 64, and 128 megabyte modules. Prices for both types of RAM are generally between $1 and $1.50 per megabyte for most modules.

A Phillips screwdriver and about 30 minutes of time are required to install a memory module.

Click here for a list of links to memory manufacturers.
 

the installation

1. Make sure the computer is turned off.

2. Carefully disconnect all of the cables from the back of your computer, place the computer on a stable working platform, and remove the outer case. Discharge any static electricity from your body by touching the computer's power supply.

3. Depending on the layout of your case and motherboard, you may need to remove the motherboard tray to gain access to the memory (usually only with tower cases). To remove the tray, you may need to remove some screws surrounding it before you pull it out. Either way, once you have access to the memory on the motherboard, proceed to the next step.

4. Carefully remove the memory module from its anti-static bag.

5. If you are installing a SIMM, your memory slot should have metal clips on both ends. One end of the SIMM should have a notch cut out of it. This end corresponds to the side of the memory slot with a plastic tab at the base. Slide the module in at an angle (usually about 45 degrees), then pivot it until it stands vertically and the metal clips snap into place. This entire step should take little force, so if you are experiencing difficulty, check the ends of the module and memory slot and realign if necessary. Repeat this step for each additional SIMM in the memory bank.

   

6. If you are installing a DIMM, your memory slot should have a small plastic lever at each end. Make sure these levers are pulled away from the slot before proceeding. The slot should also have two small bumps along the contact area (one in the center and one closer to one of the ends). The DIMM should have two notches that correspond to these bumps. Align the DIMM with the slot accordingly, then carefully push it straight down into the slot. If you have done this correctly, the plastic levers should now be pulled back toward the slot. Some DIMMs have a very tight fit, and can be difficult to install by pushing them directly into the slot. If this is the case, try pushing one corner of the module into the slot first, then pushing the rest of the module into place.

7. Replace the motherboard tray if you had to remove it, then replace the outer case and move the computer back to its original location. Reconnect all of the cables.

8. Start up the computer. If the computer appears to be functioning normally, you can ensure that the computer has recognized your new memory by typing mem at a DOS prompt. The value in the Total memory column should reflect the amount of new memory installed. However, if the monitor remains blank, turn off and unplug the computer, and then go back through the installation steps. If you still can't get your system to work, contact the memory manufacturer.