I have a seen graphics cards get upwards of 80 Celsius. The manufacturers set the cooling parameters and usually they are stable under these conditions. You can usually turn up the fan manually in the graphics options, but it would obviously be more noisy. The same card I said that got to 80c never got above 65c - 70c when I turned the fan on high.
Another thing to do is use compressed air every once in a while to get dust out of the fins on the graphics card. Usually does a lot of good on older cards.
I usually turn the fans to 70 when i run games but it only runs at 30 C on idle so Im guessing im ok. I just though anything going higher than 100 F is bad!