Could this be power supply related?

Question

I have a computer with a funky power supply. It won't turn on until something in it is warm enough. I have ordered another but a new problem has cropped up in this computer. The monitor said there was no signal even though it was connected to the computer. Thinking it might be dirty contacts I removed the video card and the monitor cable, cleaned the contacts, and plugged everything back in. No joy. I unplugged the computer and let it sit about an hour. Plugged it back in, tried turning it on but had to wait a few minutes for the power supply to start fully functioning and when it did the computer worked properly and the monitor had a picture. I left the computer on for several days and everything worked fine until this morning when once again the monitor reported no signal and once again no picture. So I removed power from the computer and removed the video card. I put the card in the fridge for abou 1/2 hour. Then I put the card back in the computer, plugged the computer back in, waited the few minutes again, and now it all works fine again. So, should I start shopping for a video card too? Could the flaky power supply be affecting the video card too? Eric

Ralph Mowery · Accepted Answer

Some of the computers have been known to have capacitors that go bad after a few years. The classic symptom is the computer comes on when hot.

Look at the larger capacitors that have leads going through the board. If the top of them is rounded off like a dome they are bad. They should be flat. This could be on the motherboard or video board.

dansabrservices · Answer

Could be in the power supply too.  Check all caps on the 5V or 3.3V lines.

mike · Answer

Put an oscilloscope on all the power supply lines and see if they look good. A typical voltmeter won't always see the problem. You can read

5V on the voltmeter and have horrible spikes on the line. Don't forget 5VSB. I've had several systems where the cap on the 5V standby supply went. Nothing else would run without it.

ohger1s · Answer

Since you've already ordered a new power supply I wouldn't go any further u ntil that's installed. If the supply is sluggish or inop when cold, it mos t likely has high esr electrolytics. Even when warm enough to allow functi on, they still allow sag and ripple on the outputs which can upset whatever is connected to it. Good chance everything gets fixed with the new supply .

etpm · Answer

Thanks everyone for the replies. It seems weird to me that the video output fails after quite some time, maybe as long as 36 hours. I looked at the caps on the video card and none have any obvious bulging or leaking. So I'm just gonna shop around for video cards and when the new power supply is installed if the video out fails again then I'll get the card I want. Eric

Micky · Answer

You're assuming that the time in fridge is what made it work when on other occasions waiting itself had an effect.

Anyhow, I once got 3 moderately old video cards for 10, inc. shipping, probably on ebay. Each failed after about 3 years but I'd rather start with a spare old card than buy a fancy one not being sure it's the problem. You could also try plugging in another monitor when yours isn't working.

I don't really think the PSU is affecting the picture, but you do have a point that getting another video card would narrow things down. So will the new ps when it comes.

BTW, paragraphs would make your post much more legible.

etpm · Answer

OK, I'll try paragraphs.

I am not assuming that the fridge treatment made the card work, but I think it may have. I just knew that it took some time being off for it to work again and I didn't know if cooling might have made it work again. I wrote what I did trying to be thorough.

Eric

Micky · Answer

That's a good practice.  Better than medium, and far better than the opposite where people leave even important things out.

Could this be power supply related?

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