Sudden black screen (not a big box issue im sure)

[floodie]

Guys not sure if this is the right section but would like anyones thoughts on this please.

Does anyone have any idea why a machine in the middle of a game would go to a totally blank screen (perhaps monitor power dropped), sound off, however Marquee and coin button lights (that are powered from USB on the motherboard) are still on. 

Also, when tapping or holding down the power button (that is wired the power switch on the mobo) does nothing either. Even the hard reset long hold.

The only way to turn it off is at the wall - Wait 10 seconds - switch back on and push the power button. After longer than usual we get the bios and it boots up however throws up the typical corrupted XLM error due to sudden power drop(which i can sort out no problem)

I am very much remote to this machine, and getting to it to get hands on will take a while. With all that diagnosis does anyone have any idea what the problem could be?... the system is still receiving power.. Perhaps the monitor could be suddenly going into an ECO mode of some kind but surely i would still hear audio and i would also be able to turn off the system with the power switch.

Could it be faulty RAM? CPU? Hard drive?? or even PSU?

Any thoughts would be greatly appreciated! thank you

David