well I use riva tuner to overclock, I have my xt at 423/731( cause it is summer and it gets hot on the second floor) in october/november, i will up the speed. but i have not had any problems at this speed(only when it is really hot in my room) but every card is different. what you need to do is to try a setting( not to high) like mine, and slowly up the speed. do all kinds of testing.if you have farcry/doom 3 put the graphics on high and test your card. if you begind to see anolomies and other things, then your card is too hot and you have gone to far, back down the mhz a little. your memory may not go very high since you have no ramsinks. keep that in mind. also, if the memory chips are really hot, then the clock is too high.
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