I'm trying to decide whether I should go DDR2 or DDR3 for my next build. For purposes of this discussion, cost is NOT as issue. Known components will be:
- Intel Q9550 quad-core CPU @ FSB 1333
- X48 Northbridge
- 4GB of either DDR2 CAS 4 or DDR3 CAS 7

I don't really intend to overclock, but I do want fast yet stable performance, and I figure you guys probably know more about this than most. My understanding is that Core 2 likes the memory to be in synch with the FSB. So, the two options are:
1. Go DDR2 and run the memory at DDR 667 (333x2) IN SYNCH with a FSB of 1333 (333x4).
2. Go DDR3 and run the memroy at DDR 1333 (667x2) or DDR 1600 (800x2) OUT OF SYNCH with a FSB of 1333 (333x4). This presumes that DDR3 can be run at 2x or 2.4x the speed of the FSB (is that possible?).

- Which option would provide better performance? Although DDR3 might appear to be the better choice, I'm not so sure given the FSB bottleneck and higher latency of DDR3.
- Is it possible to run DDR3 at 2x or 2.4x the speed of the FSB. If I go DDR3, I will be getting either a Asus P5E64 WS Evolution or a Gigabyte GAX48T-DQ6.

Thanks in advance for your time.

High-end DDR3 will give you a slight performance gain over DDR2 and the X48 chipset tends to like DDR3 more than DDR2 but in my opinion the difference isn't worth the price. Get some DDR2 800 and underclock it and tighten the timings to run 1:1 with the FSB and you will have a very fast system.

Get DDR2 and spend the money you saved on something else (better components, cooling, pizzas etc).

I would get DDR2 for now. Make the switch when you get tri-channel DDR3 for a nehalem chipset sometime in the future.

No need to run the memory at 667. Why not just OC the CPU a "little" to 400?

Will this be a gaming PC? If so why not save a lot of money and OC an E8400 to a FSB of 425 or 450, and OC some good CAS4 DDR2 to DDR2 - 850 or 900.

Really no point getting the quad atm as far as I can tell, unless you do video editing or other heavily threaded apps.

+1 ddr2 price to ddr3 go ddr2 difference of ddr3 and ddr2 not that much not worth the price of ddr3

Another vote for DDR2.

Thanks a lot for your help. Seems like DDR2 may be the way to go. Regarding the alternative:
- Do Gigabyte and Asus X48-based boards allow you to run DDR3 at double the FSB, i.e. if FSB=1333 (333x4), will BIOS allow me to set DDR3 frequency to 1333 (667x2)? How about DDR3 1600? I was thinking of either an Asus P5E64 WS Evolution or a Gigabyte GAX48T-DQ6.

- Given the bottleneck of the FSB, in what way would the higher bandwidth on the DDR3 still be beneficial?

DDR2 and P45. The core2 isn't that memory sensitive, save your money for Nehalem.

DDR3 is just not worth the price of admission, just get good fast DDR2.

Ok, Ok. But why the P45 rather than the X48?

X48, DDR3, Q9550.

DDR3 does not actually perform any better than DDR2 atm, the timings suck too much. And since intel chips like to sync RAM and FSB, might as well get DDR2, 1:1 ratio, which gives DDR2 667, which means you can tighten timings all the way to CAS 3. OP said he has no intentions of OC, which is all DDR3 is good for atm.

DDR2.