I was trying to use 8600GT as PhysX engine for ATI 4850. When I first booted XP with 8600 as second card, windows found drivers for it, started checking and then PC suddenly turned off. Later I found, that my 8600 is dead. It might be my fault, because I was using it without heatpipe at that moment, to fit it in MB. Could it be that GPU burned in such a short time? If not, what else might have caused that? It's scary to think, that some day I'll probably use crossfire and something like that might happen again...
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Yes, you need a heatsink and fan to cool a graphics card.
Some cards will beep at you and not post unless the fan is working.
But there are people who use both cards. Nvidia for PhysX, ATI for rendering. I know that I atleast need the heatsink, but does the second card realy goes in to burning that fast? It wasn't even used for graphic's...