System will constantly turn on and off without ever posting! (Bad PSU?)

[finbarqs]

Will a bad psu cause the system to:

As soon as you hit the Power Button, the system will turn on, and shut off. Turn on again (all automatically) turn off again. Turn on, turn off (repeat cycle until I unplug the power cable)

 

[Yellowbeard]

It can. But, it could also be a short. Do the "paperclip test" on the CPU. There is a How To on the Corsair forum if you don't know how to do the test.

 

[Zap]

How fast does it cycle? If it isn't near immediately, then it can be the motherboard unable to POST. A lot of boards will try over and over again.

BTW to jump the PSU with a paperclip, just connect the green wire to any of the black wires on the 20/24-pin ATX motherboard connector. This will usually get the PSU fan to spin up, with the following caveats:
1) Some PSUs don't spin up the fan until it heats up or until it loads up.
2) Some PSUs don't turn on if there is no load.
3) Even if the PSU "turns on" by spinning up the fan, it doesn't mean the PSU is fully functional.

 

[Lotheron]

How fast does it cycle? If it isn't near immediately, then it can be the motherboard unable to POST. A lot of boards will try over and over again.

BTW to jump the PSU with a paperclip, just connect the green wire to any of the black wires on the 20/24-pin ATX motherboard connector. This will usually get the PSU fan to spin up, with the following caveats:
1) Some PSUs don't spin up the fan until it heats up or until it loads up.
2) Some PSUs don't turn on if there is no load.
3) Even if the PSU "turns on" by spinning up the fan, it doesn't mean the PSU is fully functional.

Seems like a worthless test then, doesn't it

OP, best bet is to find another known good component, either that PSU on another mobo or another PSU on that mobo. That way you can isolate the faulty component.

 

[Yellowbeard]

Seems like a worthless test then, doesn't it

OP, best bet is to find another known good component, either that PSU on another mobo or another PSU on that mobo. That way you can isolate the faulty component.

No, if done correctly it's not a worthless test.

 

[finbarqs]

okay, turned on looking inside the system, the computer lights up, but no fans turn spin up. And shuts down. It just repeats this step over and over again: start up, shut down -- within 5 seconds. And it does this automatically!

 

[Yellowbeard]

Do the paperclip test as illustrated HERE

 

[BoomerD]

You don't tell us...is this a newly built system, or one that was working prior to this problem?

 

[finbarqs]

that just to show if the power supply will turn on or not...

 

[PreferLinux]

My guess would be a short. It could be the PSU, though.

To check for shorts, test with the motherboard out of the case, on a non-conducting surface and/or check for any metal behind the motherboard.

 

[thescreensavers]

that just to show if the power supply will turn on or not...

Yes, if he puts the paper clip in and it stays on with everything connected then I would guess its a mobo issue.

 

[finbarqs]

figured it out: I guess my memory wasn't plugged in all the way? or there might have been a short? But took it out, took all my memory chips out (mushkin redline DDR2) and popped in a 1GB Crucial just for testing... almost concluded that it was a DOA mobo...

But it turns out to be that the memory or mobo was touching metal!