I've been running my 8 7950's at 100% for 12 months now and not a hiccup to be had. But as with any consumer product ever made, each individual card, even in the same series, is slightly different with varying weaknesses and strengths. Perhaps I've been lucky. It's incredibly simple to just buy a new fan if one were to burn out. You can even take the chance to upgrade to a more powerful fan if you want.