I have this problem with my graphics card, sometimes (not all the time) when I am not playing any games just on the desktop/web browser 1 of the 3 fans on my Gigabyte gtx 760 (gv-n7600oc-2gb-ae) will go full speed, sometimes it will last for ages sometimes it will last for a minute. It stops after opening a game like diablo 3 but will start again after closing the game for 5-10 minutes (sometimes it wont start again). It seems really random and can happen for a few days than be perfectly normal for a week.
I have tried controlling it manually but it doesn't make a difference though the other 2 fans will speed up if changed, the temperatures are also normal. I have also checked the cables on the gpu which seem all plugged in properly.
I have had the gpu for about 4 months and its been happening for maybe 2-3 months, is there anyway I can fix it or will I have to send it back and not have a graphics card for a month which will suck and it worries me that it wont act up since its so random when they test it and will just send it back. Would replacing the fan fix it? and how hard is that to do? Thanks for any input.