Plugged the 4pin psu lead into the wrong socket, did my psu die?

[richtgc]

Had a new Antec case (with built in 450W PSU) turn up the other week. Installed brand new mobo (with onboard video), sempron cpu, heatsink and one stick of memory. When connecting up the power cables to the mobo I somehow stupidly managed to put the 4-pin psu lead (that is supposed to extend the 20-pin cable on 24-pin mobos) into the socket that supplies power directly to the cpu

On powering up there was a flash of LED activity and then silence. No dramatic boom, no calls to the fire service, but equally no working PC either. Over the past week I have replaced the mobo, the cpu and the memory to check them all out, and still it won't even get to the bios. The only thing left unchanged is the psu.

Now before OcUK make even more dosh out of my stupidity, is there any way that what I did really could have damaged just the one part of the psu? I have all new components installed so I know they work - when I hit the power button all the fans spin ready, but never does anything more (no signal is ever sent over the onboard graphics, the speaker never makes a noise).

If the PSU itself was blown then surely no power at all would flow to the mobo? That isn't the case though.. so before I replace the psu as well (I don't have a suitable spare to test it with damn it) I just wanted to know if there was anything else worth checking?

 

[richtgc]

Thanks for the suggestions. I stripped it down to just the following:

motherboard (gigabyte model with onboard nvidia 6100 gpu)
1 stick of 512mb geil ram (works in other pc)
amd sempron (arrived from OcUK today, so hopefully 100%!)
arctic cooling freezer pro heat sink (spins up fine)

That is all. I am using the onboard vga port connected to a known working monitor, although I did replace that cable too.

From the case to the mobo all I have connected is the power button, nothing else (no leds, speaker, firewire, etc). They are left dangling at the moment. I have no other devices installed (no hd, cd, graphics card, etc).

Am now at a complete loss what to try other than replacing the psu. Will dismantle another pc and try one from there I guess, nothing else happening

 

[richtgc]

"Possibly an earth (mobo touching bottom case chassis).Have you tried just running the mobo,cpu,graphics card outside case on the mobo box?"

No I haven't, that isn't a bad idea at all. I think I will try that next. Would an 'earth' cause power to flow into the mobo (enough to make the case fans + heat sink fans spin) but not actually do anything else? I get lights on the front of the case, the fans whir up, but it never progresses further.

"Google for starting the PSU without the mobo"

Thank you for your suggestion, I'm curious what this would prove though? Power must be coming out of the psu otherwise the fans wouldn't spin? I think I will swap the psu with another pc and see if that one then works (and vice versa!)

"Sorry if this is an obvious suggestion, but did you cycle the PSU switch?"

I have not tried this. I will turn off the psu from its switch and turn it back on again. However as mentioned above power DOES come from the psu to the mobo (and out into the fans), but maybe just one/two of the leads shorted?

I will get a new psu in there asap I think and see what happens. If that fails then it can only be something to do with the Antec case itself (trust me to get a bermuda triangle of a case!)