Keeps shutting down

[RoWin7]

One of my other machines, also a Win7Ult, keeps shutting down. The power button lights up, it runs 10 or 20 seconds, then shuts off. It won't restart for a while, then repeats. Is this a power supply problem, or are there other things I can test? It happened after I put in a new graphics card, but I don't know if it's a coincidence.

I've checked all the connections.
I've already tried putting in a new power cord.

 

[samuria]

It would suggest heat and it wont restart until it cools down a new card can have brought more heat. Check all heatsyncs etc for dust blockage tun with case open see if tha cures it to prove it heat

 

[RoWin7]

The case is open, the card has a fan and everything inside is clean. Now it won't start at all.

 

[RoWin7]

I nailed it. When I wiggle the cord plug, the juice comes back on, then off, then on, and it happens with 2 cords. Can you recommend a medium-priced PSU from MicroCenter? They're near me and I shop there. I need just average wattage--one HD + DVD player and I don't game.
Pentium G620
PEGATRON Mobo 2AC2 2.00
Wattage calculator estimates 221 Watts.

psu : Computer Parts : Micro Center

 

[iko22]

Just get a 350W - 400W PSU that is Bronze certified, with a 4pin+4pin PSU connector. Don't worry about modular PSU's, unless you are concerned with cabling around the case.

 

[RoWin7]

Many thanks. Just want to be sure: I tested it by bypassing the power switch by shorting green and black on the PSU. Is there a way to isolate and test the power switch too?

Did you mean "20+4 pin" connector? Hardware isn't my high point.

What does Bronze-certified mean, and will it be marked on the package?

 

[iko22]

Many thanks. Just want to be sure: When I bypass the power switch by shorting green and black on the PSU, it runs for about half a second. Is there a way to isolate and test the power switch too?

Not too sure what you are doing. You can short those pins on the motherboard. Shorting on the PSU is difficult without damaging the connector. To isolate the power switch, you would need be inside the PSU itself, if I've pictured what you are doing.
*** CAREFUL when accessing Live Voltages. Always switch off Mains and ***
*** Double check that you have done so before touching anything. ****

Did you mean "20+4 pin" connector? Hardware isn't my high point.

No. The 20+4 pin connector is for the motherboard power supply. The 4pin+4pin is the CPU supply.

 

[RoWin7]

NVM testing the power-switch. I'll know soon.

I shorted the power connector because I have no contacts on the mobo marked "Power SW." There's 1 set marked "front panel" but it has 4 contacts, and they're not labeled. I used a bent insulated wire and didn't touch anything with my fingers.

I was following a YT video.
How To Test Your Power Supply With A Paperclip - YouTube at 1:59.

None of my usual gurus are leaving the house, so I've been on my own for 4 months, which is how long the machine's been sitting. It had been my primary machine.

What's Bronze-certified?

 

[RoWin7]

Installed new PSU, except I don't know what to do with the cord marked PCI-E with 6 holes. The display card has its own fan.

Same problem. All 3 fans run about 10 seconds, then stop. I wait 15 minutes, then I can run it again, it stops. No beep codes. Then it doesn't run at all.

Case is open, no dust buildup or heat.
Re-seated the cards, check internal wires, no puffy capacitors.

 

[iko22]

Same problem. All 3 fans run about 10 seconds, then stop. I wait 15 minutes, then I can run it again, it stops. No beep codes. Then it doesn't run at all.

I had same problem once. What I did was to change the BIOS fan controller settings from PWM to analogue, and the fans worked properly again. Not sure if that option is available on PEGATRON Mobo 2AC2 2.00.

 

[RoWin7]

It doesn't run long enough to get into the BIOS or to display anything or do a beep code.
1-- Can you change the fan settings manually without getting into the BIOS?

2--Is this a clue? It happened after I put in a new graphics card, and never ran normally again. Too much of a coincidence? I thought I had loosened up something, but I hadn't. I didn't get a chance to tell the BIOS to stop using the onboard graphics and use the new card instead.

3--I've figured out the power switch connections, and shorted them. I get the same results: starts for 10-20 seconds, stops, then again, then does nothing for a while. So we know the power button and PSU aren't involved here.

 

[iko22]

Fans should run at full speed until BIOS POST has finished, I don't think you can adjust that unless you use an external fan controller to set the fan speeds.
It may well be that you loosened something while installing a new graphics card, but if a wire had worked loose, then you would expect it (the fan) not to work altogether, not even for 10-20 seconds. Check your computer's wiring anyway, and especially remove tufts of dust, should you find any.
You could of course remove the graphics card completely, and then check to see if the fans run for longer on next boot-up.

 

[RoWin7]

Doesn't run at all now, with or without the video card. Also tried popping and reinserting the CMOS battery.
No tufts of dust, I had cleaned it recently. No loose wires visible.
Whatever is wrong isn't visible.

Thanks for your time , going to give up on this. I have 2 others.