Thankfully there is not a wide range of memory standards to choose from, with DDR (Double Data Rate) memory being the only real option for desktop computers. However, this does not necessarily mean buying memory is an easy task as the price, frequency, capacity and timings of DDR memory vary greatly from one module to the next. For the moment DDR2 is the most widely used DDR specification, offering speeds between 533MHz and 800MHz. Although DDR3 memory is starting to become available, it will be some time before DDR3 replaces DDR2 on the mainstream market.

Therefore price wise the smartest and most obvious option at this point in time is DDR2, the question is how much do you need? Recently we ran a number of tests comparing DDR2 on the Intel Core 2 Duo platform using a range of frequencies and timings. The end result was that DDR2 memory when paired with a Core 2 Duo processor only needs to work at 800MHz, anything more and it is a waste of bandwidth. Furthermore timings seem to be somewhat irrelevant as CAS6 memory timings were not a great deal slower than CAS3 timings, which was a surprise.

The fact that the Core 2 Duo platform does not need memory faster than 800MHz is no surprise really. If you do the math it all makes sense and I think where a lot of confusion surrounds, is the quad-pumped 1066MHz FSB of the original Core 2 Duo processors. The memory FSB needs to match the processor FSB in order for the peak memory bandwidth to be achieved. However the Core 2 Duo E6700 processor for example, really only uses a 266MHz FSB, while DDR2-800 features a 400MHz FSB.

Therefore in order to exceed the bandwidth potential of DDR2-800 memory, you need a Core 2 Duo processor running a FSB greater than 400MHz, which only happens if you overclock a low-end Core 2 Duo. The only Core 2 Duo processors that require a huge injection in FSB frequency are the E6300/E6320 processors, both need a 427MHz FSB just to reach 3.0GHz, where as the E6400/E6420/E2140 processors only require a 375MHz FSB to reach this same frequency.

This means users should be less concerned with memory frequency when building a Core 2 Duo system, even if overclocking is on the agenda. What is important is how much memory you decide to configure your new Core 2 Duo or even Athlon64 system with. For those using Windows XP the sweet spot appears to be 2GB’s of memory, while you can use up to 3GB’s for the 32-bit version. For many tasks in WinXP you can get away with 1GB of DDR2 memory, but games work far better with 2GB. However, those wanting to upgrade to Microsoft’s latest operating system, Windows Vista, will have to reconsider how much memory they are going to configure their system for.