Really strange - it seems to happen consistently when there is activity with the on-board video, a couple of times every day or so. Suspected PSU and line power, put it on UPS (an APC XS with AVR), Still same issue. It is Windows XP SP3 on an Intel I3-570 and Kingston DDR3 10600 in a CoolerMaster Elite342 microATX case with its own 450W PSU.
Ran Memtest86+ for hours with no error. Using "safe defaults" in BIOS, removed most of startup stuff, moved swap file to another partition - still the same reboot pattern.Finding in the system Eventlog random system errors. Please help - did anyone have similar issues with this MOBO? Should I just RMA it or it might be a different issue?
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Since you have the same results with and without UPS, I advise going back basics and stress test the build.
Prime95 for an hour using CPUID's Hardware Monitor (with Detect Rounding Errors checked) to watch temps carefully. Don't let it exceed 75C continuously. If it crashes, you likely have found a memory issue that memtest did not detect.
Then Furmark stress test, not usually crucial with onboard graphics, but do it anyhow.
Then both for say 15 minutes, watching temps very carefully.