Running DDR2 800 at 1066

[joel_spencer]

I'm contemplating getting a Phenom II 940 and have a few queries about ram speed. I curently have the Corsair ddr2 xms cl4 kit

http://www.scan.co.uk/Products/2GB-(...d-CAS-4-4-4-12

(though not originally purchased here), I seem to remember that 1066 ram is only overclocked 800 so with my high performance kit is it likely that if I drop back to the standard timings for 1066 I can overclock it fairly easily.
Secondly I think my board (ga-ma 770 ds 3 rev 1.0) may only support single channel for 1066 ram so would it be better performance wise just to leave it at the lower ratings at 800?

[Blaineoliver]

Its not officially supported at 1066, but if you overclock the ram, and adjust the multiplier accordingly, you will get decent performance increase.

[scaryjim]

As an AMD-770 chipset AM2+ motherboard your GA-MA770-DS3 will happily support dual-channel DDR2-1066 memory with a Phenom CPU - it's your Athlon X2 that's limiting your memory speed.

HOWEVER, your existing memory is only rated to run up to DDR2-800. That means that, at manufacture, the chips could not be guaranteed to run consistently at a higher speed. Now, Corsair XMS is decent quality memory, so it's not impossible that it will run at 1066 - but please be aware that you're pushing it well outside of its rated limits, so there's no guarantee that it'll run that fast, and no guarantee as to how long it'll remain stable at those speeds. My advice would be to loosen the timings a lot and try running it at 1066 - if it runs stably then try tightening the timings. Although, tbh, I doubt you'll see that much of an improvement in performance (certainly nothing like the improvement you'll see from getting a Phenom II 940 vs your existing Athlon!).

One last word - if you can afford the extra £13 I'd get the Phenom II X4 955 BE (currently £145 on Scan). As an AM3 CPU it'll fit in your existing AM2+ motherboard, but give you the option of upgrading your mobo and RAM down the line to AM3 / DDR3...

[joel_spencer]

Ah you see Jim sadly the revision one of that board, which I have, does not in fact support AM3. Gigabyte did a press release saying it would but it hasn't played out that way.
However for anybody else in my boat who might be reading this, if you ask Gigabyte about it then they may (like me) be inclined to send you an AM3 compatible revision 2.0 board which features 2 more usb ports (no sieral port tho), 2 more sata ports, a slightly newer nic card and the amd 700sb. They'll also bios flash it to the latest version and everything.
Great service from them I reckon. When I get that and *touch wood* all goes to plan then I'll probably change my phenom ii 940 decision to a 955. For future options and because I foresee the AM2+ chips getting rarer and more expensive as AMD shifts its focus to AM3.

As for the ram, the losest timings I've seen are 7-7-7-20

http://www.scan.co.uk/Products/2GB-(...d-CAS-7-7-7-20

Seems very similar to my ram, what sort of voltage would be appropriate? The default for mine is 2.1v but none of the cl7 1066 kits have a voltage.