Motherboard problems

Never been here before, but I believe this is the right place to ask for advice.
I have a relatively new motherboard (ASRock H61m-VS) and processor (Intel G620) (got it for Christmas) and they have worked without any problem so far.
But half a month ago I had to move my PC to another room and then it started doing strange things. This morning I woke up to it trying to boot on its own, hours after I shut it down. It starts the fans, sometimes even the BIOS as well, and then it shuts down. About 5 seconds later it tries again, and the same thing happens.
I tried things like taking the battery out and clearing the CMOS, nothing worked. The moment I plug the power cable back to the power unit it tries booting.
Any idea? It would mean a lot to me, so please guise!

OP here.
My problem has been solved and I actually forgot about this thread.
So it seems someone must have ejaculated into the power button itself, because it got short circuited somehow. Everything else works properly and I am happy.
Thanks for the responses though, and until they don't make HALO for PC I am not going to play it, although I know it is an awesome game. Yeah.