Today while running my HD 7970 at 1200Mhz core clock on stock voltage, BF3 failed twice. No artifacts at any time, temperatures never rose above 62C, but the first time my whole system froze. The second time, BF3 crashed (giving me a DX11 error that I had seen before when overclocking my old 6950 too far) but my OS remained stable.
Curious, I ran Furmark at the same clocks and stock voltage again at 1080p with 8xMSAA. Ran for 15 minutes, no problem at all. In both times I tested in BF3, the game froze/crashed within less than 15 minutes. Do I need to run Furmark for a longer period of time? How is its reputation for reliability? Is there any other stress tester I should try that I don't have to pay for? (I've already tried the free demo of 3DMark 11 - again, no problems, but that was limited to 720p)