they are the exact same card other than clockspeed. Of course, the clockspeed is a big deal, as the GT has a 66% faster GPU and 70% faster memory. I haven't heard of anyone who has been able to take a 6600 to 500MHz speeds, but I suppose it could be possible. You'd need aftermarket cooling, though, because the 6600 cooler is terrible, and at 500MHz the 6600GT runs hot (~80C during load) even with the better cooler. Of course, if you spend $20-30 on cooling, then you might as well get the GT. Oh, and memory is not gonna be hitting 1GHz on a 6600, that's for sure. The memory is midrange DDR, like 550MHz, and considering even good DDR, like the 700MHz on the 6800, can't hit those speeds, i don't think you'd be getting anwhere near 1GHz. Anyways, the point of the story is, if you want a 6600GT, buy a 6600GT, you can't "flash" a 6600 into its big brother.