I don't think the Everest stress test is good enough to stress, compared to Orthos or Prime. The best test for stability, is running Orthos or Prime for 6hrs minimum, 8 or more hours, is preferred.
1.5v is getting pretty high. I would also not suggest running 1.8v through the Q6600. That guy, might have used phase change. As long as the temperatures are in safe range, I guess it's ok to up the voltage even higher. But I wouldn't suggest that, for 24/7 use.
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