I've recently added another GPU to my system and have enabled Crossfire, the two cards I have are the XFX HD 6850 and the Sapphire HD 6850. I've tested several games and it doesn't seem as if I'm getting the full potential.
Here's my current hardware setup
CPU - AMD FX 8150 3.6GHz (Not-Overclocked)
GPU - 2 X HD 6850's (XFX HD 6850 + Sapphire HD 6850) (Not-Overclocked)
RAM - 8GB Kingston HpyerX Blu 1600MHz
Hard Drive - Maxtor 320GB SATA II
SSD - SanDisk 128GB
PSU - Coolermaster GX650W
Motherboard - ASUS Sabertooth 990FX
I have tried several games maxed out on a 23" 1920x1080 Acer Monitor and get the following results
Black Ops 2 - 30-60FPS
Skyrim - 25-40FPS
GTA IV - 25-40FPS
Far Cry 3 - 20-30FPS
Crysis 2 - 30-45FPS
Battlefield 3 - 25-35FPS
I have the latest AMD Drivers (CCC), both cards are running in a PCI-E X16 2.0 slot, I can't understand why my FPS is so low?
crossfire is a sham. but it sounds like your having driver related issues. when adding a second card you are supposed to totally remove the amd drivers, reboot, reinstall the latest ones and download the application profiles. i sold my 6850 crossfires a month after i got the second card due to issues and bought a single better card, things are much smoother now.
no im not a lying troll, ive experieced crossfire problems, and just about every other crossfire thread comes to the same conclusion, even on paper you can see the frame latency is double that of a single card, the mirostutter is real, fps drops are real. If that is not a sham, i dont know what is. I am angry at AMD for not fixing this crossfire, it's still buggy in the latest series of cards. They have had plenty of generations to fix it and havn't.
Download a GPU monitor (you can get it for the sidebar in windows, obviously make sure you have two instances monitoring both cards)) and make sure both cards are being utilised. Make sure crossfire is actually enabled as well, it has a habit of thinking it's enabled when it isn't and try the application profiles.