Last month we discussed how to add more RAM to your system. We also discussed some of the different kinds of RAM such as SDRAM (synchronous dynamic random access memory), DDR (double data rate), RIMM (Rambus inline memory module), etc. (No - etc is NOT a type of RAM). One of the things that remain the same is change. This is true with RAM also. With this in mind, each of the above types of Ram (I tire of Caps easily) is subdivided by speed.

For example, SDRAM comes in PC-66, PC-100, PC-133, etc. varieties denoting the speed in megahertz at which it runs. You can find the speed of SDRAM you need in your manual or at the motherboard or computer manufacturer's website.

DDR comes in a great variety of speeds. The speed, however, is not posted prominently on the Ram - nor is it advertised. DDR comes in such speeds as PC2100 (266Mhz), PC2700 (333Mhz), PC3200 (400Mhz), PC4300 (533Mhz), etc. Seem confusing? Don't let it be. Read on.

All you have to remember is to keep your computer owner's manual(s) handy. Major computer brands list the Ram type you need. If you have a "white box" specialty computer, be certain you get the motherboard book from the builder. This holds true for every other component in your specialty computer.

I know. This seems too complicated. It is! Instead, simply write down this kind of information somewhere convenient to your system so you may look it up if necessary.

A note about RIMM. Most, if not all, RIMM can be found in earlier Pentium-4 systems. This is (or was) particularly fast Ram that required special motherboard circuitry. You cannot swap or substitute RIMM with or for other Ram. If your computer uses RIMM (Rambus memory), you want all your Ram to come from the same manufacturer and in the same configuration (i.e. all 64MB, 128MB, 256MB, etc.). Also, RIMM must be added in pairs. So if you want to add 256MB of RIMM you must add 2 sticks of 128MB each. Another "also". If your motherboard has 4 memory slots with only 2 containing Ram, the other 2 must contain "continuity" sticks. These sticks have no actual Ram on them, yet provide electronic continuity to the memory circuits. These are particularly critical requirements for RIMM memory.

Other types of Ram can be added one stick at a time, although they should be from the same manufacturer, in the same configuration, and running at the same speed. For additional info about Ram, visit the following sites on the web:

http://www.crucial.com/store/listmfgr.asp?cat=RAM

Next month: Laptop Ram.