I have 8 7970 cards running in milk crates with box fans on them.  2 of the 8 cards have started to have fan issues after running 24/7 since May.  I've seen/read several different opinions on how to fix this. Unfortunately I don't have the boxes to RMA these cards, the rigs came pre built.  Is it crazy to just remove the plastic housing including the GPU fans and let the cards just be cooled by the box fans I have setup next to the rigs?