I solved what might be a similar problem last evening by lowering the speed of my i7-3055K (nominal 3.9GHz) to 4.2GHz from 4.5GHz.
My symptoms were similar: new PC build (10 days old); crashing or blue screens about 1 minute into a 3 minute Premiere export or AME render, Win7 Pro. The system had previously been very stable. At first I suspected an H264 codec problem or an iTunes/Quicktime incompatibility but when an AVI render using the NTSC DV Widescreen preset crashed it broadened my search for solutions. Mercury GPU render on/off did not fix the crash problem.
The render last evening was probably the first time that my new CPU was seriously stressed. Lowering the CPU speed was the quick solution. Overclocking sites/forums probably have tips on stress tests, memory tests, voltage tweaking, etc but as long as the system is stable I'll probably be satisified with the slower CPU solution.
The CPU cooling is the Intel stock fan. 32GB of Corsair memory is running at its rated PC1600. CPU and memory voltages are the defaults, i.e., no tweaking. Intel DZ77RE-75K motherboard. EVGA GTX680 FTW+ 4GB at its defaults, i.e., no overclocking/tweaking. 1000 watt power supply , which is probably overkill but it's what I had lying around (I have an almost identical setup (GTX460 rather than GTX680) which runs fine at 4.2GHz with a 700-watt PSU -- but I've never stressed that 2nd PC with an Premiere/AE/AME render).
