BSOD VIDEO_DXGKRNL_FATAL_ERROR (113) after new 6850 install

Hello

I've got a machine that bluescreened yesterday while putting a new XFX 6850 through its paces. Machine had been back up about an hour, I'd installed latest AMD drivers, ran OCCT's GPU stress test on error check mode for half an hour or so without issue, and then was running Unigine's Heaven DX11 benchmark tool on loop to check out performance & noise/thermals. I returned with some food 30 min later to find the machine BSOD'ed. Tried for about an hour to replicate the BSOD without it recurring.

MSI H55M-P31 v1.9 BIOS
Intel i3 540 @ 3.67ghz (160 bclk)
2x OCZ3G1333LV2G @ 1280mhz 9/9/9/20 tRFC 88 2T
Windows 7 x64 Ultimate SP1
640GB Western Digital

I've got a few other computers I can test the card in, just trying to track down any other potential causes first.

Thanks for the help

No serious dust deposits, CPU has a Hyper212+ cooler (heatpipe+fan), but I dislike the case's overall airflow design, will try to see if I can improve somehow, perhaps better fans/control

CPU runs rather cool, ~47 C full load (linpack) even at its current overclock.
GPU temps seem adequate, 'idle' at 36-42 C, full load with OCCT was ~75 C
temps while running Unigine Heaven benchmark loop were ~66 C

Mobo TMPIN2 reads 31-32C at idle, 35C @ full CPU load, 38 running Heaven, and reached a peak of 41C with OCCT GPU test. I'm unsure what this is on H55, just that its not CPU.

will reseat & reinstall the card/drivers

Edit: previous cards were GTS 250 & HD4850, with furmark load temps of ~80 and ~85 respectively