We've already given our general recommendations about choosing system memory for Core 2 Duo systems in the course of this review. So, you should be aware by now what characteristics of DDR2 SDRAM modules are to be taken into consideration when you are building your computer with a new Intel processor with the Core micro-architecture. In case you've missed something, here are the main points.
First of all we have to acknowledge the high efficiency of data pre-fetch algorithms implemented in Core 2 Duo processors. It is thanks to them that platforms with such processors have data access latency comparable to that of Socket AM2 Athlon 64 systems, which feature an integrated memory controller. However, notwithstanding the impressive achievement of Intel's engineers, the memory subsystem of Core 2 Duo systems with an external memory controller, located in the chipset's North Bridge, cannot match the memory subsystem of Socket AM2 systems in overall efficiency. To be exact, the platforms with new Intel processors cannot provide as high memory bandwidth as the competing platforms do.
The memory bandwidth on Core 2 Duo systems is limited not by the characteristics of DDR2 SDRAM modules but by the bandwidth of the bus that connects the CPU with the chipset's North Bridge. This is why your changing the memory frequency or timings is going to have a small effect on performance of a non-overclocked Core 2 Duo system (but the frequency influences performance somewhat more than the timings do).
More interesting are the results of the overclocked platform. In this case, there is more sense in using fast memory and the optimal memory frequency divisor is 1:1 (FSB:DRAM) as has been shown in our tests. In other words, you can achieve maximum performance by using memory with lowest possible timings in synchronous mode. It means that if you overclock the FSB to 400MHz, DDR2-800 SDRAM with low timings is the optimal choice. If the FSB is overclocked more, DDR2-1000 or DDR2-1067 SDRAM is the best option. An additional argument in favor of using memory and the FSB in synchronous mode at overclocking is that the 1:1 divisor is the most stable one on a majority of mainboards.