PC died at the weekend

Hey everyone, I hope you can help me  

I have an old (2 year old) Alienware Area-51 i7 920, 6gb ram, gtx260 1.8gb, 2 Hdds (750+1TB), asus Mobo and Asus sound card 5.1.

Over the weekend I fell asleep in the evening with my PC just playing a TV show. In the morning, it was dead.

What I did:

Unplug and then plug, and try, nothing.
Tried removing all parts and cleaning, and trial and error with what to replace whilst checking if system worked. Nothing seemed to help.
Did the remove the battery thing on the Mobo, no help.

Strange things:
Mobo has power and reset light lit up
Case fans and lights spin for half a second and lights flash but then die.
Tried friends PSU from almost identical system (mine is 750w PSU, his was 650W), nothing happens apart from PSU fan almost starts to spin (like a jolt)
Tried my video card in my friends PC (both gtx 260) and didn't want to even recognise it.

I have a feeling either Mobo died, issue with PSU (yet why does friends not work either?) or video card died and is causing issues.

Require anything let me know, currently at work though.

Thanks!