Only thing I changed was the board. I'm not exactly sure what the cause is but my FPS in games on the abit board was a bit 'jumpy', as in it wasn't very consistant. After getting the dfi board going my FPS is games is much more consistant and more enjoyable.
I was using the newest bios, I also used a modded bios for extra ram dividers.
'officially' opterons are not compatible with desktop boards, they're intended for servers. unofficially they work fine and the opty 165-180 are identical to the x2's (the optys just have higher testing standards from what I understand).