Maybe it is ur GPU overheat, did you overclock it?
Sometimes when it overheat too much it just crash and restarts,
some times it is not just the GPU overheated, it might be the
southbridge of the motherbaord
my 3870x2 did not give overheat syndromes like crashing or wad,
it just continue to run till it shows me artifacts(distorted lines
and boxes of ur image) and i took it for 1 to 1 exchange.
If ur card is still under warranty, u should bring it down for
RMA, before anything else bad happens
nowadays overheat will auto shut down one ar?? i still remember
last time.. my video card the fan brokedown...... then got
fire..then i still online... still chatting... till i smell some
burning smell.... i still got time to tell all those ppl i am
talking to that my cpu is on fire... but.. no one believe mi ..
knn.. then i shut down lor...... cannot on after that.... need to
change card lor..