power on then off again

[childsy_1985]

I just put together an older pc. So far as I know the parts are all good well they where supposed to be. Now when I connect the power and hit the switch the psu and cpu fans spin, the led lights on the cpu cooler come on but then within a second it powers off and I get nothing. I have to turn it off at the power in order to repeat the power test.

I have tested the power supply, which is new, and it works fine. Everything is connected correctly so far as I can tell. Only thing I can put it down to is a possible short on the MB or have I missed something. Anyone have any helpful suggestions?

 

[johnb35]

Did you install the proper amount of standoffs between the case and motherboard? Are they only where they need to go?

 

[childsy_1985]

yeah its a micro atx board and has all the propper holes filled

 

[Okedokey]

Reset the CMOS.

 

[Geoff]

How did you test the power supply? This happens quite a bit, and if it's a new build chances are a component has failed. Usually either the PSU or MB.

 

[childsy_1985]

i tested the psu without having it connected tothe mb

 

[Geoff]

i tested the psu without having it connected tothe mb

So how do you know it's good? Did you just short two pins and see if it starts up? It could be a problem when put under load, or with certain rails.

 

[Okedokey]

Reset the CMOS.

Try this first

 

[tylerjrb]

I just put together an older pc. So far as I know the parts are all good well they where supposed to be. Now when I connect the power and hit the switch the psu and cpu fans spin, the led lights on the cpu cooler come on but then within a second it powers off and I get nothing. I have to turn it off at the power in order to repeat the power test.

I have tested the power supply, which is new, and it works fine. Everything is connected correctly so far as I can tell. Only thing I can put it down to is a possible short on the MB or have I missed something. Anyone have any helpful suggestions?

If theres no beeps etc? Id say take the cpu fan/heatsink off, remove the cpu and make sure its seated and installed correctly, square with the arrows pointing toward each other on the socket and cpu . Make sure none of the pins/pads are damaged, bent etc on both cpu and motherboard. If no damage is visible make sure theres no dust, debris inside the socket or on the Cpu itself. Something like this sounds like its the CPU. If its powering everything up but just not doing anything then powering straight off.

Id also make sure the motherboard is correctly installed and standoffs are not overtightened or loose. and make sure the heatsink isnt overly tightened.

regards, Tyler.b