Computer not posting

[Ernie101]

I installed a new new heat sink (noctua nh d 14) on my friends computer after his all in one watercooler pump packed in. He could post to windows before but had warning sounds frmo the cooler so he kept ift off since.

Unfortuantely his case didn't have rear access to the cpu backet on the back of the mobo. Which was fine, so I took everything out (gfx, mobo etc) unplugged it all to install the heat sink.

Everything went fine and it posted and went to bois so I could check the temps, again this was fine at 28 idle.

Then the screen went black randomly and wouldn't post. Restarted numerous times, but still nothing. Reset the cmos, nothing, tried each Ram stick in pairs, nothing, tried both cards by themselves (285 gtx sli), nothing.

I then noticed that the graphics card fan wasn't spinning up properly, and only moved when I gave it a helping start. So I then tried the other card and it does exactly the same thing???
Tried the other pci-E power lines and still the same.

I've got no idea what to do now? psu problem?

I've not seen this before and I'm pretty stuck as to what it could be.

specs
i7 920
285gtx x 2
6gb patriot RAM
2HD in raid
750W psu (can't remeber brand think its corsair)

any ideas please.

 

[Ernie101]

Yeah, I reassembled it outside the case on anti static bag so I could access everything better. Still the same. I think psu or mobo as you say. Will have to try my psu.

 

[Ernie101]

I did reseat the hsf already. good point about power on the water pump. Will check pump on my psu power and see if it goes. Will be around his house later, will keep an update in how it goes.