Psu failure? Help please

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Slasher

144 posts

Master Geek

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#285877 22-May-2021 16:31

Hi all

Could someone please provide some advice on my rig

My long time rig is not responding to the power button.

I noticed last week when I turned it on it boots up however the graphics card wouldn't light up so I would hard shit down at the wall and give it a minute and start again. After a couple tries it works absolutely fine. Then again happens during the next power up attempt.

Now it's not happening at all. I'm assuming its the psu?

Mobo green light comes on and lan light blinks but no response to the power button when pressed

PC is plugged via power surge multi box

It's a rm 850i corsair

Mobo is m5a99fx pro 2.0

Any advice is appreciated, thanks in advance

Delphinus

611 posts

Ultimate Geek

#2711431 22-May-2021 16:46

Try unplugging PSU from the computer and see if it will start up by itself if you short the green and black wires.

https://www.instructables.com/How-to-power-up-an-ATX-Power-Supply-without-a-PC/

Then you'll at least know if the PSU is definitely faulty.

OzoneNZ

102 posts

Master Geek

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#2711444 22-May-2021 17:28

Dodgy power button/switch on the case maybe?

You can bridge the power switch pins on the motherboard with a paper clip to rule that out

rb99

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#2711468 22-May-2021 17:33

Try different power cable ?

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rb99

linw

2849 posts

Uber Geek

#2711569 22-May-2021 21:23

"so I would hard shit down at the wall". Could be your problem right there.

SpartanVXL

1306 posts

Uber Geek

#2711706 23-May-2021 12:54

If it used to work okay but now is not responding but as you mention still has power running to lights etc. you may have a short somewhere.

I would recommend taking the psu out to test by itself like Delphinus says. Then clean out your case, check the power button cable to make sure it still works. Maybe safest thing to do is take everything out of the case and run it on a wood/cardboard surface to confirm

Last time something like this happened my GPU was shorting and the psu wouldn’t start because it was tripping a safety circuit. I foolishly held the button for 10sec+ and magic smoke started coming out.

Slasher

144 posts

Master Geek

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#2711830 23-May-2021 19:38

lol just realised linw 🤣

Thanks for the replies all.

I tried swapping the power cable as the frist thing and it worked.I thought I fixed it for good as it was responding for the whole night as I tested it. But the next day the same issue came up lol.

So its back responding and starting up again but only after a few attempts shutting down at the wall.

Will try as suggested with the psu test and report back :)

Slasher

144 posts

Master Geek

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#2728853 14-Jun-2021 23:13

Tested out the psu as per the link/youtube. seems its working fine, fan turns on/off.

I noticed when i reconnected the 8-pin EATX12V connection it worked, then turned off to test again and same issue (pc will not turn on).

Turned off the psu, disconnected the 8-pin EATX12V and reconnected and tried again, it worked.

Not sure if this information helps at all.

Sometimes when the pc starts but the gfx card does not start I have noticed that the cpu led (red led lablled cpu_led) in the motherboard stays on.

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timmmay

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#2728870 15-Jun-2021 06:24

I had a faulty power button once. Diagnosed by shorting the pins on the motherboard.

1101

3122 posts

Uber Geek

#2729112 15-Jun-2021 13:51

its an AM3 motherboard.

Its old , so no surprise you have issues (My AM3 board also has intermittent faults)
With my old AM3 board , when it wouldnt power up (wouldnt POST) , I had to move ram to another slot . Then back again next time it failed .

You'll need to do some proper diag : with a NEW PSU.
Also remove vid card and try another known good card
Try with some other RAM .

Pull out all the cables, USB , sata , audio , power button cable , reset cable etc . Start with a paperclip across power on pins (as suggested above)
Also look for broken USB ports .

Start seriously planning for an system upgrade . :-)

frankv

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#2729117 15-Jun-2021 14:09

From the above, it sounds like it starts up OK if it's been sitting for a while, but doesn't start up if recently running?

So I wonder if it's some kind of thermal shutdown?

Or a thermal disconnect (e.g. a crack in a conductor that opens up when warm)? Maybe try gently wiggling boards and chips and connectors to see if you can make it recur or go away if it has happened.

kitfromoz

11 posts

Geek

#2732358 21-Jun-2021 22:26

One cheap test option would be to get a second hand cheap PSU from a computer recyclers.

Like @timmmay I also once had a customer with a faulty switch on her desktop case. I didn't realize until installing a new motherboard and the problem continuing. But that was only once instance in 15 years of repairing computers..