Fubarred 8800 GT?

[enaberif]

So I just recently bought a XFX 8800 GT card and did a bit of overclocking on it, nothing major and then I put a aftermarket heatsink on it which everything has been working fine. Tho in the last few days playing games I get hard lockups and have to reset the computer and can play again.

So I figured up GPU-Z and it say my card was at 600/900/1512 when stock is 600/900/1500. So I loaded up RT and looked and it said it was set to 600/900/1500 and I'm likeSo I loaded up the monitor in RT and sure enough it said it was running at 1512.

So I decide to see what happens if I drop my clocks from 1500 down and if I drop it to 1498 my clock drops immediately down to 1458 which I know is not normal.

So the question I ask is something like this normal? Or do I possibly have a faulty card? And please nobody say that it was or is due to the cooler or overclocking cause I know neither did this.