Artanoon' chaps! I'm experiencing some odd behaviour from a system I'm trying to do a modest overclock on and I wonder if anyone with more expertise can assist. It's a Q6600 in an MSI G41M-P28 (I think, might be -P25), cooled by a Corsair H75 (maybe H70) AIO and with 1600MHz DDR3 memory. I initially couldn't boot with an FSB higher than 323, but that freq worked and ran okay for an hour or so in Prime95, with CoreTemp reporting numbers under 52. When I tried running Prime95 for longer though, I came back to find the screen off and the power light flashing, which I thought was a sleep mode, but I couldn't wake it up other than by turning off the PSU switch and restarting. Oddly, shifting the box around tended to make it turn off, then restart so I thought something was loose, which touching the pump appeared to verify. Tightened the cooler bracket up, restarted, all good. Even shook the actual box about to test for other loose bits, but all seemed well. Except I started getting hardware failures in Prime which resulted in reboots, so I reduced the FSB to 322, then 321, both with rounding errors on different cores. Hmm. Thought I'd try closer to stock, just to check it was otherwise okay, so ran the FSB at 280 and...back to the flashing power light again. I have no idea what's causing this - I can't adjust the voltages as there is no option to do so, but according to CPU-Z it was topping out under 1.3v when at 9x323, so nothing major; the RAM is running at 12xxMHz (sorry, can't remember exactly), so under the 1333MHz OC the MB is rated for and well under the 1600MHz the memory is rated for. I've checked the Prime log and nothing in there indicating hardware failure (other than the abovementioned), I've checked the Windows System log and no errors in there indicating critical failure or shutdown activity, I've eyeballed the temps for a bit whilst under load and nothing over 55/56, I've looked at the highs in CoreTemp but it must reset itself as these say about 45, can't find a log of CoreTemp anywhere and now I'm stuck. Why is it shutting off? Why is it only doing it sometimes? Incidentally, it doesn't seem to be doing it in normal use (although it did shut itself off with a flashing light a couple of times whilst I was updating Windows, but hasn't since). Is it RAM related? Help!