PC started to reboot in cycle. As soon as it reaches POST step 89, it reboots. Even if all periphery is disconnected (with only keyboard, CPU and RAM). Motherboard is Gigabyte GA-X58A-OC. Has anyone encountered such behavior?
It shouldn't be a compatibility issue if you had been using it. It could be a board or cpu failure. Do you know anyone with a similar setup so you could try your cpu in another board and try another cpu on your board.
Did you have a video card in the system when the problem started happening? did you recently disconnect your pc from the monitor before the problem started? Try it with the card in and try using different ports on the card to connect to your monitor. The dvi cable or dvi to vga adapter plugged into the wrong socket could also cause your issue.
Problem solved. For future reference - the source of reboot cycle - keyboard. I don't know what happened with it while I was at work, but after disconnecting keyboard pc starts normally. Only now I realize that never disconnected it from motherboard during all previous tests. Hope it'll help somebody.