PC turns on and shuts off in tenth of second?

[PCTechie316]

I've had this problem in the past, but i seemed to fix it each time, but this time i cant get it to work. I was trying to put a cable in my pc the other day and when i moved my pc forward a little, my pc shut off right away. Now when i try to hit the power button, my fan lights will flash on, then turn off. This has happened to me in the past, where i would go to turn on my pc and it wouldn't put no power.

Then i would rest the cmos on the motherboard, a few times, and it would boot up. This time, i went and bought a new 500 watt power supply and the same thing happened. Now i put the new power supply through my power supply tester, and i couldn't get the -5 v to light up, but my old power supply would light up all green. So I think either both power supplies are bad, or the motherboard is shot, or I think some piece of metal is hitting the case, and is causing a short. If the short problem, will my pc work once i fix the metal piece or screw that might of fall behind the motherboard. I think i should take the pc completely apart and plug everything in and see if it works, if it doesn't boot, then I duno what to do. What do you guys think could be the problem?

 

[SNGX1275]

I think your new 500 is broke, it always suprises me how many defective power supplies make it out of the factory.

I've seen computers shut down like that before due to static discharge, but usually letting them rest with no power for a bit (minute or 2) and they will come back on.

I really doubt your motherboard is toast. What I'd do is return your bad 500W and possibly get another one, stick the power supply in, reset cmos, and try to boot up. If that doesn't work, remove and reapply the heatsink on the processor (reapply thermal paste) I'm not sure it would shut down that fast if it wasn't getting a good connection but it might be worth a shot. If that doesn't work, remove the motherboard, make sure you are using the motherboard offset (spacers) so none of it is touching the case. Make sure none of them are missing.

If its still broke you could try minimal booting by disconnecting all but the absolutely essential components (ram, hd, vid card) and adding things back one by one.

Did you try the old powersupply after unplugging it from the wall for a bit and resetting the CMOS? Or did you just get the 500W when it didn't work.

 

[Tedster]

a $12 PSU tester works wonders, but I would return the defective PSU.
Read Tomshardware.com for PSU reviews and ratings. Brand and prices have no bearing on quality although no-name brands are a guaranteed way to get a loser.

 

[PCTechie316]

I FIXED IT LOL. I took everything out of the case except the mother board and the mb screws were all in tact, but i found one screw that i dropped awhile back, so i said theres the problem. So i plug the hard drive in, and hit the power button. Boom pc booted. So i plugged everything back in, and boom, pc did not start. So i took out everything, and put in one by one. Found that when my Ethernet pci card was in, the pc would not boot. So i thought it was a bad pci slot, so i plugged it in other pci slots and boom pc did not turn on. Then with the card out, boom pc turned on. So I don't understand how that pci card would cause the pc not to boot. But oh well, i will return the power supply and but a new Ethernet card tomorrow, thanks for the help guys.

 

[Tedster]

1 screw dropped onto a powered mobo can destroy it. Yoo may be lucky.

always use a magnetized screwdriver when installing parts. mechanics fingers (tool) are also helpful for dropped items.