A plead for help; Newly built comp will not start.

[Cirandi]

I recently decided to build a new cheap mid-range comp...

Asus PN5 Mobo
Intel E7200 2.53GHz Core2Duo CPU
Corsair 550W PSU
2x1 GB Kingston RAM
Asus radeon 3850 GFX
500 GB Hitatchi Spinstar SATA HDD

Not the first time i build a computer, but i've encountered a problem i've never seen before.

After i assembled it everything looked fine, LED on mobo is green... But when i try to start it all the fans spin for a fraction of a second and then shuts down. All of them start, chassi, PSU, GFX, and CPU.

No beeps indicating hardware failure but i've tried a few things. Removed the parts one after one trying to find out which one was playing up, but when i was down to just mobo and 1 stick of ram and no change what so ever i'm out of options.

Tried clearing CMOS to no avail. Any of you recognize this problem or have any idea of what it might be? Guessing it's mobo or PCU, tried with another (480W) PSU and the exact same thing happens.

[Overdriven]

Check the jumper cables. That bit usually gets me, was the cause for my issue. Just make sure they're all in the right place.

[TdC]

oh and make sure your cpu's heat sink is fit correctly and that the thermal paste is in the right place

[Helme]

Might be abit stupid suggesting it, but I've seen it many a times, people forget to connect the 4x power cable to the motherboard - it's usually located to the "left" of the CPU

[Cirandi]

Originally Posted by Overdriven

Check the jumper cables. That bit usually gets me, was the cause for my issue. Just make sure they're all in the right place.

You mean jumpers? Yeah i checked them... Haven't tried replacing them, gonna try that when i get home.

Originally Posted by TdC

oh and make sure your cpu's heat sink is fit correctly and that the thermal paste is in the right place

it's in the right place, but nothing is running long enough for the PCU to overheat. The fans just jolt into motion and then immediately loses power.

[Cirandi]

Originally Posted by Helme

Might be abit stupid suggesting it, but I've seen it many a times, people forget to connect the 4x power cable to the motherboard - it's usually located to the "left" of the CPU

It's connected

[Raven]

You should also make sure you have the power button/reset etc all connected properly to the motherboard. I always get mine wrong and end up having to mess about with them.

[Kryten]

Take it all out of the case and give it a run, sounds typical of a short underneath the motherboard. This is often down to a bad part in the case, rather common even with the higher end ones.
If not, try without any ram at all - it wont start but it should stay powered up and beep 4/5 times.

[Yaka]

most of the time its not the case unless its a no name brand one. i used to find most of the time its the metal spacers and no washers between the screws an mobo. its rare that this a problem these days tho