Well, it seems I am another miner that has suffered a fan failure on one of my Sapphire 5850's
I have three of them, and one of them started becoming unstable while mining, and would intermittenly just stop hashing, so after troubleshooting, I realized the temps on one particular GPU would just shoot up right after starting a miner. Within few minutes I realized the fan was barely spinning, and causing the GPU to overheat. I cant get the fan to spin any faster by software means, so I am assuming its dying like the many others.
So, I am RMA'ing back to Sapphire. Has anyone had to do this before? How long did it take before you got yours back?