So I had the same problem with my XFX 7950( 3months old). I contacted XFX support and they offered to send me a replacement fan to do myself or send it in for them to do it.  If I f-up doing myself, warranty is voided. They stated its easy, just need phillips and thermal paste.  Im pretty good with tinkering in electronics.  Any advice on which route to take?  Can I seriously f-up this unit by just replacing the cooler?  Any advice would be appreciated.