after few more testing on 5970..
I find out that both GPU are not using full power in Crysis.
the GPU usage running around 60-70% on both core, and I doubt my Q6600 @ 3.6G is going to bottleneck it... not quite sure what happen here.
also, I am having the exact fps when I turn on 8xAA compare to 0xAA... that is something even more odd to me... and some custom map like "Photorealistic" have like 20fps compare to 25-30fps I got on single 5870... uh.
It could bottleneck it in some parts. I have a few saves at level parts where there is a lot of AI running around, and it can stress a core of my i7 920 at 3.8 to near 100%. Bumping the proc up to 4.1 provides a boost there.
Of course, this will depend on your resolution and settings. I found that 5870+5970 do not handle crysis warhead at 2560 very well at all. There is serious thrashing whenever I turn around which I suspect is from 1GB of memory not being enough.
Also, at 1920x1200, the 5970 was in the 90% or more range most of the time. Adding the 5870 dropped the utilization into the high 60% range but only improved FPS a bit. It seems like multi-gpu 5XXX configs can easily be bottlenecked by both the processor and their vram (should have gone for 1.5 GB).