6800XT hangs on Windows Vista

[UrbenLegend]

I have just installed a biostar 6800xt with the 163.39 drivers. I have been trying to play halo 2 and fear, but both freeze about 5-10 minutes into gameplay. Its a complete hard lock (num lock doesn't respond) and I am forced to restart my computer. Sometimes, rarely, it would blue screen and give me a irq_not_less_or_equal, or a pagefault something. Anyone know what's going on? Its a brand new card and brand new memory too.

Much help appreciated. :P

[UrbenLegend]

In fact, every modern game I have tried freezes. I have just tried the Quake Wars demo and it froze 5 minutes into a game. How do I find out what's going on?

[UrbenLegend]

I have tried underclocking the card and it seems to be a lot more stable. But I don't want to do this as i am losing performance. I am not even sure its because of overheating problems as I have felt the heat sink and it didn't seem very warm. Are there any alternatives, such as increasing fan speed? Also I am unable to check the temperature from ntune or riva tuner. I have heard of a way to enable that with the 6600 gt by modifying the bios. How do I do this for the 6800xt?

[UrbenLegend]

I have decreased the clock speed from 300 mhz to 281 and left the memory clock speed at 532 mhz. It seems to be fairly stable for now, although I have only tried halo 2. If I upgrade to a 7600 gs would it give me more heat problems?