Ok i have Abit KN9 nforce4 ultra based board, on the market there are cheap 1066Mhz ram memories like the Kingmax 1066Mhz 1gig Ram for 50$.

So my question is will these memories going to be compatible with my board?

Thanks in advance!

The RAM should be backward compatible i.e. you can run it slower than rated.

ram support is incoming from your memory controller.
which is in your CPU in all amd systems.

ddr2 is supported.

abit website specifies 800mhz to be the best frequency supported.
so the bios settings shouldn't exceed 800mhz.

amd's website specifies in the general AM2 spec pdf 400mhz (ddr2 800)
http://www.amd.com/us-en/assets/co [...] /43042.pdf

if you get 1066 mhz ram, set the bios default to 800. also, your system could end up being unable to boot with it.

your best choice, 800mhz with a lower latency.

1066mhz will only be handled by the next generation motherboards.
but by then, integrated controllers should support ddr2 and ddr3 but on another, more versatile socket. integrated mem controller was good on S939 while it limits now as memory is upgrading faster.

thanks for the replies,
but my question is will i be able to run the memory full speed 1066Mhz with my chipset?

It depends on not the chipset but the MB.
DFI MB's always OC better than any other brand.

Only if you can achieve a 533MHz FSB overclock(i.e. 100% overclock on a C2D 6xxx). I'm not even sure that's possible on a core 2 extreme 6800. Quad pumped like Intel likes to describe it's FSB, that means 2133MHz. Stock is 1066.

edit: I guess I'm assuming you want to stick to 1:1 ratio.