Computer Boots up then shuts down

[wolf0x]

Well I began to build my new computer to day and when I finished and tried powering it on it started up for 5 seconds then shut down and rebooted I do not even get anything to appear on my screen. I believe the most likely cause is that the psu is not powerful enough (specs below) as I unplugged the graphics card from the computer and it went from 5 sec to shut down to about 15 secs so I though this made the possibility of my CPU overheating unlikely and also it restarts it self I do not have to unplug it etc. Any help with this would be great.

Pc specs:
Intel i3-530 with stock cooler
Gigabyte GA-H55M-UD2H
Radeon hd 5770
4gb corsair
400w corsair PSU
One seagate barracuda 7200.12
2 120mm fans

 

[MadAdmiral]

That PSU is plenty powerful enough. Have you made sure you've plugged everything in? Do all of the fans spin up (case fans, the CPU cooler's fan, GPU's fan, PSU's fan)? Did you attached the heatsink properly?

Really, that's about all we can do for you. That and point you to the standard troublehooting thread. The link's in my signature. That will cover nearly everything that can cause a build to not boot properly.

 

[wolf0x]

All the fans in the case spin

 

[MadAdmiral]

What about inside the case? The actual case fans aren't that important. The one that really matters is the CPU fan. If you don't have a case with a window, leave the side off and try again.

 

[wolf0x]

Just tried it again the CPU fan spins as well

 

[MadAdmiral]

Ok, then go through the thread I mentioned above. There really isn't much we can help with without more information, which you get when you go through all of the steps in that thread.

 

[wolf0x]

Just tried a old a reliable PSU which is 450 W and the pc did the same thing

 

[wolf0x]

Took off cpu's Cooler and the thermal paste did not look like it was put on right ( it was pre applied on the cooler