Re: Tri crossfire 6950's
It will work but it will drop the resolution of the 30in down the that of the two 24in. So all 3 will run at 1920x1080 or 1920 x 1200 depending on which 24in you have.
Heat shouldnt be to bad just bump the PCIE fan up before you game. Say 30% - 40% and see how hot they get. You can go more if you need to but it will start to get loud around the 40%+ range.