Memory or RAM (random access memory) is one of the more important things inside of you computer. Where do you think all of the information you computer is using goes to be stored for a short period of time? That's right it goes into your memory. There are different kinds of memory. EDO, SDRAM, DDR-SDRAM and RDRAM to name a few. Basically what RAM does in short is holds variables and information that programs need to run, then when the processor needs the information it calls it off of the RAM. This is why it is very important not to be cheap when it comes to memory. I would rather have a 900Mhz computer with 256MB of memory rather than a 1000Mhz computer with only 128MB. If you need to upgrade your computer because it is slow, look at upgrading your memory. Games seem to suck the most out of your memory. As they are constantly writing and recalling information off of your system memory. When your memory gets full, it gets erased and written over. You cannot store files on memory, nor can you access it. It is just there, so don't worry about what is going on inside of it. When you turn your computer off the memory is erased off of the RAM, that is why sometimes all you need to do is restart you computer and things will not freeze up as much.
RDRAM comes in three speeds, PC600 (300Mhz), PC700 (350Mhz), and PC800 (400Mhz). You can never have too much memory no matter what kind it is, right now RDRAM is competing against DDR-SDRAM in speed. Overall DDR-SDRAM is faster than RDRAM, but it is very expensive compared to it. However RDRAM will pull slightly ahead of DDR-SDRAM when you are running it in dual channels. I explained how that works in the processor section. Basically in Dual channel mode you will be getting twice the memory bandwidth so with RDRAM PC800 like what I am using, you will be getting 3.2GB per second rather than just 1.6GB per second. 128MB of memory is the standard now days. However in the future when Operating Systems get more complex and programs and games get bigger and better you will need more memory. Some people will also say that if you are running too much memory in your system it will slow it down. That is nonsense The more memory that you have the more you will be able to do on your PC.
I give PC800 RDRAM a 90% on greatness. When I purchased it I got two 128MB RIMMs of Samsung memory at $330 a piece. I would have given it more, but it is over twice as expensive as SDRAM PC133, which runs at about 50 cents a MB. RDRAM will cost you over a dollar per MB. It does run a little hot, as you can see from the picture, it has aluminum heat sinks mounted on it. This is great, if you have the money to spend on it then get a system that uses RDRAM.