73 degrees is normal.
What I meant was have you tried other software, like phoenix or diablo miner. There is a possibility that video card is faulty, but I think other causes are more likely. I wouldn't send it to manufacturer, because if you are wrong, you'll waste a lot of time and just lose money for postage. If I were you, I'd find another computer to try that video card on. I, for exampl,. have a motherboard which refuses to operate if gpu gets above 80 degrees.
What OS are you running? If it's windows, try LinuxCoin distribution. It's very easy to start mining