Over the past few months we have published quite a few DDR2 memory related articles that looked at how timings, frequency and capacity influence the performance of Intel’s Core 2 Duo processors. The results did not really surprise us, though many of the readers did seem shocked by our findings. First of all memory timings (latency) make very little difference, as CAS 3-3-3-8 T1 delivered just 5% more memory bandwidth at 800MHz when compared to CAS6-6-6-18 T2 timings. In almost all games this made near no difference, particularly at higher resolutions such as 1920x1200. So memory timings are somewhat irrelevant for Core 2 Duo systems then.

This was a little bit of a surprise but what did not surprise us at all was how little of an impact memory frequencies had on performance. Now to make a point we ran the processor on a 500MHz FSB, which means at a 1:1 ratio the memory would be working at DDR2-1000 and because we used an nForce 650i SLI motherboard we could go as low as 667MHz. When it came to bandwidth performance the DDR2-800 configuration actually produced the best result thanks to the T1 timing, which was not used by the DDR2-1066 or DDR2-1181 memory modules.

So even when overclocked the Core 2 Duo processors really only need DDR2-800 memory to produce results. That said, Intel chipsets such as the P35, P965 and 975X only allow users to select a 2x multiplier or higher, so on a 500MHz FSB the memory must run at 1000MHz or greater. When it came time to game, the DDR2-800 memory was every bit as fast as the DDR2-1181 memory despite the processor operating on a 500MHz FSB. In fact, even the DDR2-667 memory produced similar results to the modules clocked at 1181MHz.

For as long as I can remember it has always been best to run the memory at a 1:1 ratio with the processor. So back in the days when the Pentium 4 processors used to use a 200MHz FSB, it was best to pair them with DDR-400 memory which also used a 200MHz FSB. However, when DDR2-533 came along, processors had to step up to a 266MHz FSB to fully utilize the bandwidth and eventually they did, when the Core 2 Duo processors using the quad-pumped 1066MHz FSB came along. However now we have 1333MHz quad-pumped FSB Core 2 Duo processors which can theoretically achieve a peak memory bandwidth of DDR2-667 memory.

Therefore these 1333MHz (333MHz) processors are best paired with DDR2-800 memory which offers a little more headroom. This is not a problem given 2GB of DDR2-800 memory is dirt cheap and readily available at the moment. Essentially DDR2-800 will cater for processors using up to a 400MHz FSB and since no standard AMD or Intel processors use a 400MHz FSB yet, there really is no need for memory capable of speeds faster than 800MHz; unless you are overclocking beyond a 400MHz FSB. That said, unless you own a Core 2 Duo processor with anything less than an 8x clock multiplier, chances are there will be little need to exceed a 400MHz FSB. So now let’s take a look at the DDR3 situation...