Dead PC - Was screaming for its life... Any ideas?

I have no idea what forum i should of put this in, cant really find much for "support" (though i remember there was a support forum at one time.. maybe im just having a blind day!) but if a mod could help out that would be good, anyway....

Well i've not used my PC in months & decided to move it into my living room and make it my project to transform it from gaming PC to abit of a gaming / media center.

Anyway, i bought it downstairs a couple of weeks ago, powered it up all fine, decided ill put Win7 on it as it has a nice media center.

Everything seemed to be going fine, Apart from when the PC was left on its own for an hour or so it would go into standby and the graphics card would SCREAM (8800GTX), a fire alarm volumed high pitched squealing sound which in my experience only happens when a molex wasnt plugged into the card (Which are secure) this has happened 4-5 times over the past week, i made a post an hour or so ago on the GFX/Win7 forums asking for advice, but since then things have progressed.

And well, a couple of hours ago it screamed so i shut it off (its too loud to bother trying to fix it there & then, its painful)... And 30mins ago i decided ill power it back up, try to look at the power settings & see if i could tell it not to turn off the graphics card or something... Pressed power button.... nothing.

Checked cables/power (lights on mobo are on, so i know thats fine)... pressed button again, nothing.
took case off & used the on-board "On" button, nothing.

Unplugged / replugged / new cord giggled some cables on the mobo etc.... pressed button, nothing.

I cant say as ive ever had a PC just "die" on me, usually theres a beep or something trys to power up but this is completely dead, but lights are on the motherboard so i assume theres power going around.

Any ideas?

(I assume PSU is buggered, but £100 to replace... urgh, not doable!)
Typical this happens when Aion is 8 days away!

PSU failure.

Cables are connected etc, its strange the thing works fine... just when the PC goes into standby it screams.

I think daship is right, PSU looks pretty dead.... will be trying a spare PSU tomorrow to see if it powers up, if it does ill setup the RMA etc. (Realised OCZ offer 3-5year warranty!)

If it doesnt, buggered if i know what ill do