New PC ran for 10 minutes, then completely died (no bios/video, yes beep/fans)

I was installing windows on this new PC, which I was switching on for the first time. It was working fine for about 10 minutes into the installation and then it suddenly it shut off and tried to restart. It got as far as the little PC speaker beep, but about a half-second later it "clicked" off. Since then this failed start just loops over and over again until I switch off the PSU (pushing or holding the panel power button does nothing). All the fans (and the VPU light) turn on for the half-second, but no signal is sent to the monitor and there are no noises other than the fans.

Then I unplugged everything except the mobo (and with it the processor of course) and case fans, and now it does the same thing except it lasts 3 seconds each time instead of one.

So since it runs a bit longer with less things to be powered, is it safe to assume it's the PSU?

Unfortunately I can't check the PSU with another comp because I don't have anything else with a 24-pin power plug, and vice versa checking the new comp with the an older PSU.

Anyway, sincere thanks anyone who recognizes this and can point me in the right direction. I want to be confident when I take the offending part back this morning (not the least important reason for which being that I bought them all at different places)

Fwiw:

Antec NeoPower550
Asus P5Q-E
SAPPHIRE RADEON HD 4850 512MB
Intel Core 2 Duo E7200

 

Welcome to MG.

If you have a multi meter you could check the PSU voltages.

See this for details.

 

Check and make sure that the CPU fan is properly seated down properly as it might be overheating the CPU. The fans that come with Intel CPUs IMHO are meant for the trash. I've never had good luck with them.

 

Thanks!

After all I found that it runs fine on top of a cardboard box. So I must conclude the problem was being caused by some kind of short.

 

Good catch RR! Double check that you dont have a motherboard standoff in the wrong part of the mobo. Shorts can be hard to track down. I once had a PC that ran fine on a box, would not work in the case. I tried everything. Eventually gave up and got a different case. Worked perfect after that!:confused