Computer will not power on ???

[seamorton]

This is an older Desktop pc using XP 3. Was gone for a few weeks an upon return The desktop will not power up. Power supply checked out ok, the MB battery was replaced. There is a green light that shows up on the MB when the power supply is switched on. PS fan does not come on and the monitor does not power on when the on/off switch is activated.

Everything worked satisfactorily when I left. Would appreciate any an all suggestions our family forum members can offer to see if what I may be able to do in order to get this unit revived. Thank you for taking the time to assist with this matter. SM USAF 62-66

 

[Thebobo]

Any beeps?

 

[VirtualLarry]

Corsair PSU test video

https://www.youtube.com/watch?v=5FWXgQSokF4

 

[seamorton]

Any beeps?

Nothing that I can hear

 

[daveybrat]

Well it's either a bad power supply or a bad motherboard. Just because you're getting the green led light on the motherboard doesn't mean the power supply is good. It takes a minuscule amount of power to light that little green led, so that doesn't mean that the power supply is still good.

You'll need a known good unit just for testing.

 

[RLGL]

disconnect all drives ,Remove the ram,
remove all add on cards...what happens when you try to boot?
BTW have you heard beeps in the past at start up?

 

[seamorton]

Well it's either a bad power supply or a bad motherboard. Just because you're getting the green led light on the motherboard doesn't mean the power supply is good. It takes a minuscule amount of power to light that little green led, so that doesn't mean that the power supply is still good.

You'll need a known good unit just for testing.

Replaced & tested the unit with a tested power supply with the same results. There was a power outage while we were away.

 

[seamorton]

disconnect all drives ,Remove the ram,
remove all add on cards...what happens when you try to boot?
BTW have you heard beeps in the past at start up?

Removed ram & disconnected all drives with the same result. No beeps in the past or present noted. Guess I'll have to get back to the basics again and keep you all posted. I was told that we had a power outage while we were away??

 

[VirtualLarry]

If you have a power outage, was this PC connected / protected by any sort of surge suppressor or UPS / battery backup? I had a friend lose an SSD to a power blackout event. If it was browning out before you lost power, it could have damaged something if it wasn't protected. In that case, nearly anything in the PC could be suspect, although the power supply usually takes the brunt of it, followed by the motherboard.

And if you've tried swapping in a known-good power supply (and didn't forget to plug in any of the cables - did you get BOTH the 24-pin ATX, and the 4- or 8-pin ATX12V/EPS12V connector?), then the only conclusion is probably the motherboard, RAM, or CPU, with the motherboard most suspect. If you remove the RAM (all of it!), does it beep at you?

Also, do you have any sort of speaker / chirper attached to the SPKR 4-pin header on the board? If not, get one, it will help diagnose.

If you've got a known-good PSU, and removing the RAM doesn't make it beep when you attempt to POST, then either the motherboard or CPU is bad, and you can test that by swapping a known good one. Best to test the CPU by moving it into another known-good mobo, and test that way. There is, a small possibility that either of them could be "walking wounded", and damage the other part, should you test them. This can be tested, by having a pair of similar CPU and mobo, that are both known good, and try swapping them, and if your test rig no longer boots, then something was damaged by the components under test. In that case, both should be tossed / recycled.

Chances are, if you remove the RAM, no beeps from mobo, that the mobo is bad. (Still, possibility of putting in a new CPU and testing, if it works, it was the CPU.) It's fairly rare for a CPU to fail, though, even if the mobo is shorted.

I'll be frank, this could be a rabbit-hole of tech-support, and given the age of the system, pull the HDD or SSD, and replace the whole rig. (Save the working PSU.)

Oh, and if you remove all of the RAM, and have a speaker connected, and it DOES beep, then that generally means the RAM is bad, and the mobo and CPU are good, because it beeps in the process of POST if it doesn't have RAM available. So that means that the CPU has started to execute POST. Which is a sign of life for the components. Swap in some known-good RAM, and see if it boots, then.