Testing my 2 HD 6850's for faults?

Chaos Water

Distinguished
Jan 7, 2012
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Recently I've seen a performance drop on my 2 HD 6850's in crossfire. I do not think I'm getting the full potential from both cards and cannot understand why.

If it helps my hardware components are

CPU - AMD FX 8150
GPU - XFX HD 6850 & Sapphire HD 6850 (Crossfire)
RAM - 4 X 2GB Kingston HyperX Blu (8GB Total)
MOBO - ASUS Sabertooth 990FX
PSU - Coolermaster GX 650W
Monitor - Acer GR235H 23" 3D

Are there tests I can perform to see if there are any faults?