i7 build suddenly dead

[L33]

Hi all
recently put together an i7 rig for my other half for her design work, has been working fine for a few weeks since I built it but this morning when she went to power it up for a day working from home it appears dead
By 'dead', I mean it turns on, fans spin up and board lights up etc but after 4-5 seconds it powers off.
I had limited time before I had to leave for work myself, but I tried the following:
- BIOS reset/clear (multiple times)
- Removed graphics cards, RAM (tried single DIMM in different slots), disconnected all HDDs etc
- Disconnected PSU from board, left it 10 minutes
- Removed motherboard from case and tried booting up with just CPU and single ram stick

No matter what I tried, the exact same thing happened. No beeps from the speaker either.
Nothing is or ever has been overclocked or modified as this is a 'work' machine, its also connected to a decent surge protector/UPS so I can kind of rule out a power surge.
Any ideas what this can be or anything else to try? I'm leaning towards dead motherboard/CPU or possibly faulty PSU but don't have any other compatible components to do any trial and error style swapping

Specs are as follows:
Core i7 920 D0
Asus P6T Deluxe
6Gb OCZ DDR3 12800
Sapphire Radeon 4890
PC Power & Cooling silencer 750W crossfire edition
etc etc

Any help much appreciated

 

[Plec]

You seemd to have covered all you can with the time and components you had to hand.

I would try a different PSU (i know you havn't got one - but beg, borrow, or steal one if you have to) and if it's still the same it's looking a lot like a mobo problem as you've ruled out shorting with the external set up.

A gfx card would be handy to try too - but obvioulsy this isn't an option if you can't get hold of one.

Without spare components it will be a bit hit and miss with diagnosis - but the PSU or Mobo are strong contenders.

Good luck.

 

[L33]

Thanks for the reply, was thinking the same thing myself
Does anybody know whether these boards would normally emit any beeps with NO cpu ram or graphics card installed? That way if I could try it without those bits, I would be able to narrow it down some more.
Thanks again

 

[Blackwhite]

Are u using any UPS?

 

[ShaolinDreams]

im leaning toward mobo.. try getting some ASUS support.