+1 "adjust the fan curve" from Deemo
EVGA makes a very nice OC utility. I use it. EVGA PRECISON. google it. It will let you set the fan curve. Start by just forcing the fan to 100% and see how the temps drop, then pick a curve that works for you. You can also play with mild OC.
Aside, how long have you had the card? (670 - probably not that long) After a while the heat sink on the GPU can fill up with dust, you need to blow it out with a can of compressed air. That's worth 5 degrees last time i did it. A can of compressed air is $7 at stables, home depot, or mail order from amazon or newegg.