No, I didn't try that. But I reinstalled WIN10. Installing drivers right now. Until now - 0 errors (YoWindow installed and running).
Could it be a software issue then? Just asking, because BSOD 124 seems to be strictly hardware failure. Before formatting hal.dll also started crashing anlong with ntoskrnl.exe.
I'm going to send MOBO anyways because I suspect that error "BOOTMGR is missing" is caused by this board.
I'll post back the results later.