I can confirm that an OC'ed 9800GX2 is not enough to run the game in DX10 mode with everything maxed, even if using no AA. I'm getting 10-15 fps less than I do in Crysis(V.high settings). The game just puts a crazy load on the GPU. Supposedly it's playable with a 4870X2 though, even when using 2-4xAA.
Turn off the Dx10 effects and the game's fps go sky-high, even if it doesn't look *too* different.
One interesting thing is that the game seems to be practically single-core only. When playing, only one of my cores would have 100% load, the rest were at 5%'ish.
However, the game does appear to take good use of dual GPUs. Judging by the core temperatures, both my GPUs were working at 100%. In the game's console the game also properly detects and activates dual GPU mode, which would explain why the 4870X2 and the 9800GX2 takes the lead on the 280.
interesting. good scaling for multiple GPUs but poor CPU scaling. so I plays better in DX9 as well, I wonder if that is a bug in their engine or what.