Pc wont turn on after I turned it off with the mains (wall)

Hi,

This morning i turned on my pc and connected a new monitor to it via my gpu, my other monitor was on and suddenly turned off. I had no signal from both my monitors so i could not see what was going on or what had happened, so i tried turning off my pc by holding down the power button for several seconds.....and nothing. Waiting around for a few hours i had enough and turned off the pc via the wall mains socket and left the computer off for another few hours, came back to find Pc does not turn on at all, opened up the case to find the green motherboard light was turned on and yet the pc was still not turning on. So i started with taking off the gpu and other pci cards to see if it would make any difference, it did nothing. took off the psu and tested the psu with the old paperclip trick and it worked fans started spinning so im assuming the psu is working fine. I also checked all the connections to the motherboard, took them off, reinserted them cleaned up the dust etc and yet nothing the last thing i done was i checked to see if the case power button was faulty.....it wasn't. any ideas as to what the cause could be and how to resolve the problem?

Any replies will be appreciated

Thank You

Thanks for the reply,

No, after the compter stopped turning on i took off the monitors and tried to turn it on...no luck, then i took off everything else (gpu, sound card and other pci cards) and left the motherboard with ram and a hard drive connected....still nothing, took off the hard drive...still no luck. Im beginning to think its the motherboard. After testing the psu with the paper clip i am sure the psu is fine, i am not 100% on how reliable the paperclip trick is though meaning if the psu turns on with the paper clip inserted into the green and black holes does that mean i rule out the psu as the cause of this or can a psu still be dead even after it turned on with the paper clip?

Yes the motherboard Led turned on but nothings spinning at all, also no beeps from the motherboard just the green Led is lit up.

No harddisk spins and i have three, no beeps from motherboard just the green light. i hope its just the Psu and not the motherboard. Thanks for the quick response Golden.

Thanks for the reply guys,

I will do what you stated Essenbe and remove the ram to see if i get any beeps, I will also try what you said Paul, will taking the cmos battery out effect my bios setup or anything else?