Your card just blows air around inside your case, take the 120mm fan on the back of the case and have it exhaust air out of the case. You want to get that hot air out of the case not try and push cool air into the case hoping it will force the hot air out. By exhausting the hot air cool air outside of the case will find its way inside by cracks or any mesh on the case.
As for your card 80*c is within specs, if you can try and take the card out and blow any dust out of the fans or fins on the cooler. I think most of your problem will go away once you switch your fan around and lower your case temps.
:update:
according to Nvidia the 670 will do 97*c before it will start to throttle the cards speeds to help with cooling, although 15*c does not sound like a lot your 82*c is well within specs. Nvidia cards will handle up to 105*c before they start to hurt themselves.
Also look into msi afterburn and make sure your fan speeds are set right. At 80*c your fan speeds may only be running at 80-75% since it has not hit the high limit for temps. With msi afturburn your can change the fan speed profile to help with cooling by setting the fan speed to 100% at 80*c if you like.