Bit the bullet and stuck another 6950 into my pc, but not getting good performance from BF3 (worse than just 2 cards!).
Got a p8p67 pro motherboard with 3 pcie 16 slots, but have had to force the bios to run the last slot at x4 speed, normally set at x1 (something that disables the pci slots/esata and usb3 connections).
Have reset my original cards to stock settings and shaders and am running Afterburner to ensure the same core and memory speeds across the cards, along with the On Screen Display to monitor temps/usage etc....
Updated to the lastest drivers CCC 12.1 with 11.12 CAP3; done this several times now after uninstalling, cleaning and sweeping.
CCC showing 3 way crossfire; GPUz showing 3gpu's enabled on the first two cards, but disabled on the last (from Google this may be a glitch in the program).
Running the Heaven DX11 benchmark gives me an expected increase in score/fps, and from the AB overlay I can see all three gpus kicking out 99-100% usage; so I'm assuming crossfire is working?!
Anyway, the problem is the bad performance in BF3; looking at the AB overlay I'm typically getting the following usage:
Changing settings from LOW through to ULTRA doesn't improve game play, OR FPS!?!?
What am I doing wrong, or am I at the mercy of poor drivers?