So I just installed my sapphire 7870 OC, after replaceing my power supply for an Ultra X3 1000w (an older model on clearance) I am now getting random system restarts. Could it be the older power supply? I am about to take the psu back to the store tomorrow, hopefully they will refund my money or at least give me store credit... if it keeps on happening I guess i will know for sure, but are older power supplies known to cause these shutdowns when paired with newer gaphics cards??