System Power Problems

[AoL_Is_My_EnEmY]

Hey all,
I just built a friends computer, but when I went to power it up it goes on for 5 seconds and then just shuts off. I've tried starting the computer with two different powersupplies but, I've had no success. I've unplugged several things in the computer and still no luck. Would could be the problem?

 

[Stugots]

you probobly mounted the heatsink wrong. or you connected the fan connector to something other than the cpufan and theres an option in the bios that powers down the computer when there is no cpu fan present

 

[AoL_Is_My_EnEmY]

the heatsinks fan starts spinning though, but ill check that out

 

[D3v1an7]

I agree with above poster, It definately sounds like a thermal protection issue.

 

[AoL_Is_My_EnEmY]

i remounted the heatsink and now it works fine, damn amd keeps changing the stock ones, thanks guys!