Hi!

Which type of memory to choose is one of the least important questions for most PC users:

1- the gamer. Modern (usually 3d) computer games are rated by their frame rate, which depends most heavily on the speed of the rendering engine on the graphics card used. Communication with the graphics card is limited by the AGP bus, not the speed of main memory. Hardcore gamers will therefore upgrade the graphics card one or two times in the lifetime of their computer. The 512Mb 133MHz SDRAM sticks are very cheap, so they usually prefer loads of memory, and turn off virtual memory completely.

2- the M$-Office-user. The amount of memory is important, because Windows/Office tries to cache every single DLL it loads in main memory, even if it's not used anymore. Since the Win32s API was introduced, every proces get it's own copy of each DLL, while the old 16 bit API in Windows 1/2/3 shared at least the code segments en resource data between processes. But, as most of this memory is only accessed very infrequently, less memory combined with a fast harddisk (and a large, static swapfile for virtual memory) is also an option.

3- users that use large datasets, for example high resolution pictures, or data from MRI scanners, or the data gathered by the Hubble telescope. Analysing such data sets is fastest if first of all the dataset fits in main memory, and the main memory is as fast as possible. Programs used for those things are highly optimized to read from main memory in large bursts, so memory latency is unimportant. Those applications are not usually ran on PC's, but if you had to use PC hardware it would definitely be a Pentium4 with RAMBUS memory at this moment.

4- the programmer. Compiling large project can be very slow... Best is to have loads of memory (for diskcaching, if you are using Windows you should change the ridiculously low upper bound of 4Mb) and a harddisk with very small seektime. (Windows 3/95/98 commits all changes to disk after exactly 4 seconds, effectively disabling disk caching if your build takes more than 4 seconds, I have never found a way to disable this behaviour and I don't know if newer versions have the same problem: I switched to linux... gcc was about five times faster than the Intel/bcc32i compiler, and the code ran a bit faster too, on my PII/233MHz@300)

My conclusion about memory types: RAMBUS is the fastest memory type (available for PC hardware at least) in raw speed, but the latency of RAMBUS is much higher that the latency of SDRAM and it is also much more expensive AND you have to buy a Pentium4 which is also very expensive. So unless you have very specialized/optimized applications for working on large data sets in main memory: you can get as good performance from cheaper system. (As soon as the data is retrieved from disk, this will be the bottleneck, in that case one should buy a fast harddisk, not fast memory.) The raw speed as well as the latency of DDR memory is slightly better than SDRAM, and it is only slightly more expensive. If you buy a mainboard which supports DDR, buy DDR memory. If you can find a much cheaper mainboard which satisfies your needs, use it to buy a good 7200rpm harddisk instead of a cheap 5400rpm version.

Hope this helps...

Post your choice of components, your budget (and how strict your limit is ) and which applications you plan to use on it. You'll get feedback if you make an "obvious" mistake. Make it clear about which components you would like feedback, or everyone will give a prescription of his/her personal dream-machine!

alex