(and my god, your temps are shocking. I thought you said your case had good airflow? Both of my GTX260's only get up to 45C when playing BC2 on full settings with the fan set to 72%)
???? 45C is shocking to me, that is insanely low, most high end GPU's would be lucky to idle at that temperature.
70-80c is more what I would consider normal after an hour of playing under a decent load, with good, not great, but good cooling.