E8400 CPU & DDR2 RAM Speed

I suggest that you get a DDR2-800 with 4-4-4-12 timing. There is no point in getting a DDR2-1066 because some motherboards cannot support up to such speed (and some motherboards that do, are memory specific, meaning they allow some RAMs to go up to that speed but not all). Unless you plan on overclocking both CPU and RAM, DDR2-800 with tighter timing such as stated above makes much more sense.

http://www.valueram.com/datasheets [...] LK2_2G.pdf

You can check out this RAM. I've been using this for a month now and it is solid.

You should also give us more information on your current set up.

Well, you won't notice a HUGE difference between DDR2-1066 and DDR2-800. Instead, it serves better for flexible overclocking, especially on boards and do not have a wide variety of DRAM ratio. However, if you plan on overclocking up to DDR2-1200 or even 1300, then 1066 is the way to go as you won't stress it as much as you do to a 800.

If you do not plan to overclock, I'd advise you to stick to DDR2-800 with tighter timings. 4-4-4-12 is better than 5-4-4-15 but the margin is small.

Like the RAM ragsters suggested, it can run at 1066 at normal voltage. That means as soon as you plug it in, it will run at 1066MHz without any tweaking (I am unsure about this RAM but if it is designed to run at JEDEC specification 1066MHz@1.8V, then as soon as you plug it in, it runs at 1066).

Some RAMs on the other hand can support up to 1066 but require voltage bumps to around 2.1~2.2V.

Also, tightening timings requires a voltage bump too. Hope this helps.

You're welcome