Computer won't boot when I stand it up?

[C42]

Alright, so I got my new build together.. installed vista, started o/cing and whatnot. So I was satisfied where I was at and decided to stand it up (It's easier to reset cmos etc with it on its side).

So I go to stand it up, powers down. I think hmm maybe something came loose? I make sure all the connections are good, try to power it up... it'll only power up for a second then just go into a reboot cycle where I have to turn off the switch on the psu.

Only thing I can think of is the cpu cooler is stressing the motherboard too much? Its a noctua nh-u12p. Thing is... it has a back plate which I used to install it, and it appears to be very secure, also with their design you can't over tighten it. I got a good spread of thermal paste on there, not too much, but enough that it covered the processor evenly.

So the system is:
Asus p5q motherboard
Intel e8600 processor
G.skill pc8000 4gb ram
Visiontek 4870 Vid card
Samsung spinpoint f1 750gb hdd
Noctua nh-u12p cooler
Corsair 750tx psu
Cooler Master HAF 932 case (Yes... it's a beast)

 

[Slugbait]

Something probably wasn't mounted correctly or whatever, so the mobo is touching metal when vertical.

 

[corkyg]

Did you use fiber washers with your mobo screws?

 

[C42]

Thanks guys, I didn't use any fiber washers because the mobo didn't come with them. I don't think that was causing it though.. I found that I accidently put an extra standoff on the case, and I think that was contacting the mobo and causing it to short.... Hooray for an upright case.

 

[lenjack]

Fiber washers not needed. Either a short circuit or an open cricuit. I think you solved it.