Once upon a time, I had the same problem as you with a far older computer.

We had an original Pentium/60 and we had left the computer on overnight playing flight simulator, and when we woke up the next day, the computer was doing exactly the same thing as yours. Result was that the power supply and the CPU had to be replaced (or so my Dad told me).

You might want to check your CPU to make sure it's still alive. I've seen the same thing symptoms with a cooked processor.

I guess you answered your own thread.

I would doubt the CPU or memory - you should get some suitably coded BIOS beeps.

IIRC this is a slightly common problem with Asus A7V333 mobos, maybe others. Are you running stock or do you have any o/c or o/volt settings? You could try setting everything to standard, check the CMOS battery is OK (remove & check with multimeter), clear the CMOS etc. For some A7V333 the only solution was an RMA.

I had to RMA my Asus CUSL2 because of a similar problem.

They fixed it OK, but I really don't rate their customer support, hense my move towards an all Intel bord this time.