Really strange - it seems to happen consistently when there is activity with the on-board video, or as a matter of fact any activity, even light, a couple of times every day or so. Just rebooted again. 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, case microATX CoolerMaster Elite 342 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, no recurring error code. Please help - did anyone have similar issues with this MOBO? Should I just RMA it or it might be a different issue?