Computer will not turn on at all, bad PSU? Ideas??

Kabob

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The past few days I've been been having an issue, sometimes after putting the computer to sleep or turning it off it will not turn on when I hit the power button. Previously I turned my power strip off and then back on and this remedied the issue temporarily, the computer would start after doing this.

Last night though I arrived home and the computer would not start at all. I tried cycling the power, I've opened the case and checked all the power connections, etc. The motherboard is lit up like its receiving power though.

Note, the computer had zero issues maintaining a powered on state, it would only have issues trying to boot up.

Where should I start looking for the fix? I don't have a spare PSU to test it but I assume that's the most likely candidate. Any chance it could be the watch battery on the mobo? Something else entirely?

Thanks in advance for any ideas!
 
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unreal89

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I know that I had issues with waking my computer from sleep because I ran modified video card drivers. Once i cleaned those out, and installed the official ones, the issue went away.

You can jump the power supply on. Disconnect ALL of the PSU connections, then take a paperclip or piece of wire and jump the GREEN and any BLACK wire on the 24 pin motherboard connector.
 

Tsumi

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Green to black on the motherboard pin using a paperclip. Really not that dangerous or that hard.

Try wiggling the motherboard connector, seems like it might be having trouble sending the "on" signal to the power supply.
 
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I had an HTPC with a very similar issue. Was stable during use but a successful reboot was progressively haphazard and ultimately failed. I went the route of troubleshooting the PSU via the paperclip and I could make it power on, then more time passed and eventually I had to replace the mobo. I left all the PSU connectors plugged into their original ports and on the mobo 24-pin connector, I jumpered from the top the green/black wires. Do at your own risk. For me, it was the mobo. I Ebay'd another of the exact same make/model so that Windows wouldn't need to be reloaded. The PSU was fine but I replaced, too, since it was already about four years old and I needed more SATA connectors.
 

Kabob

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I played with all the connections to the mobo, they all are tight as I could get them.

Maybe I'll try jumping, so I put the jumper into the PSU's mobo cable and it will start, then I take it out and reconnect everything connectors?
 

Tsumi

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Disconnect everything <--- very important.

Then connect a few fans to the molex cables to make sure you can tell it turns on and is delivering power properly. Then jump it.
 

Kabob

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Disconnect everything <--- very important.

Then connect a few fans to the molex cables to make sure you can tell it turns on and is delivering power properly. Then jump it.

Hrm, I think I can do it but I'm nervous that I'm gonna destroy something. If it does jump does that narrow down which piece the culprit is?
 

unreal89

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Also, i dont know if you checked this yet, but maybe the power button wire has gone bad...
 

Tsumi

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If it jumps successfully, then it most likely (doesn't guarantee) means the power supply is good.
 

Kabob

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Also, i dont know if you checked this yet, but maybe the power button wire has gone bad...

My mobo has a power button on it, I tried starting it directly that way, nogo.

If it jumps successfully, then it most likely (doesn't guarantee) means the power supply is good.

So if it boots the PSU is probably good, mobo is bad?
 

Kabob

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Alright, so I jumped my power supply and it came to life. Does this mean my mobo is fried? Any other tests/remedies or do I go on the market for a new mobo?
 

Tsumi

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If you feel safe doing this, connect the motherboard power, cpu power, etc. Then, using a paperclip, carefully bridge the two power switch pins on the motherboard. This will determine if the power switch is bad.

Alternatively, connect the reset switch and see if it powers on.
 

Kabob

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If you feel safe doing this, connect the motherboard power, cpu power, etc. Then, using a paperclip, carefully bridge the two power switch pins on the motherboard. This will determine if the power switch is bad.

Alternatively, connect the reset switch and see if it powers on.

Any chance you could go into more detail on how these are done?

Also, if I've tried starting it from my mobo's onboard power button, will this bypass that step?
 
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chrcoluk

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I was going to say your psu died but jumping worked.

This means one of 2 things.

1 - as others said your power switch system is messed up.
2 - The board with everything connected is rejecting power up due to detecting something is wrong.

You need to test which it is so you know what to do next.
 

Kabob

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I was going to say your psu died but jumping worked.

This means one of 2 things.

1 - as others said your power switch system is messed up.
2 - The board with everything connected is rejecting power up due to detecting something is wrong.

You need to test which it is so you know what to do next.

Alright, so what's the next step?
 

Tsumi

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Any chance you could go into more detail on how these are done?

Also, if I've tried starting it from my mobo's onboard power button, will this bypass that step?

If your motherboard has an onboard power button, go ahead and use that.
 

Kabob

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If your motherboard has an onboard power button, go ahead and use that.

I've used it, tried it many times. Nothing happens.

So my question was if I've already tried it with the onboard power button is there a need to bridge the motherboard power pins?
 

Tsumi

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Most likely not, since the power button on the motherboard should be working. You can try it, but I doubt it will help.

Do you have a spare computer you can test things in? That's really the only way to narrow it down at this point.
 

Jorona

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Just because jumping worked doesn't mean the PSU is fault free. It may not be supplying a PG signal to the board, and thus the board won't post.
 

unreal89

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Just go buy a PSU from best buy or frys or something, try it. If it works, you know its the psu, if not, then just return it. Also, I would try removing everything except 1 stick of ram and cpu/cooler and see if it changes anything. If not, I think its time for a new MB.
 

Kabob

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Just go buy a PSU from best buy or frys or something, try it. If it works, you know its the psu, if not, then just return it. Also, I would try removing everything except 1 stick of ram and cpu/cooler and see if it changes anything. If not, I think its time for a new MB.

I'll pull some RAM, I assume I also leave my disc drives unpowered to just see if my mobo will fire? Also, my brother in law lives nearby, I may swing by tonight and test my PSU on his tower.

Just because jumping worked doesn't mean the PSU is fault free. It may not be supplying a PG signal to the board, and thus the board won't post.

Makes sense. So if I try it on another computer and it does start, as well as pulling everything but 1 stick of RAM is it a pretty good guess my mobo is dead?
 

Tsumi

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Yeah, if you put your power supply in a different computer and it works, it most likely means a dead motherboard.
 

Kabob

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Alright, took my PSU over to my brother's place and plugged it in to his mobo only. Lights came on the motherboard. Clicked the power button aaaaaaaaand...nothing. Nothing at all. So I guess my next step is to borrow his PSU and see if I can bring my beast to life, I'll try it tomorrow.
 

Tsumi

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Indeed, looks like a dead power supply. Troubleshooting computers can be a huge pain, especially when you don't have spare parts.
 

larrymoencurly

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Tsumi said:
If it jumps successfully, then it most likely (doesn't guarantee) means the power supply is good
My mobo has a power button on it, I tried starting it directly that way, nogo.

So if it boots, the PSU is probably good, mobo is bad?
An ATX PSU that starts when jumpered can still have a dead voltage rail that prevents the mobo from working.. You really need to measure the voltages on the red, yellow, and orange wires. If they all measure good, then the PSU is probably fine (also a very small chance the Power-Good signal could be bad -- look for +5V on the grey wire).
 

Kabob

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Alright, I was planning on going back to my in-laws this evening with my tower but I got to work and asked our IT department if they had a spare, they could only muster up a 300W PSU out of an old Dell but I figured for powering just the mobo it would be enough. Sure enough it was, plugged it in and flipped it on and then hit the on-board power button and the beast came to life. Looks like I get to buy a new PSU.

Thanks to everyone for your help!!
 

chrcoluk

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yes looks like PSU however I am confused now with when you said it worked by jumping.
 

serpretetsky

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yes looks like PSU however I am confused now with when you said it worked by jumping.
jumping a PSU by shorting the green and black wires doesn't guarantee the PSU is properly outputting the correct voltages at the correct currents.

All it really guarentees is that the PSU provides enough voltage and power to power its own fan and led :p.

However, if this test fails then you know that you have a bad PSU.

It's one of those "if the test comes back positive you have new information, if the test comes back negative you haven't learned anything" tests.
 
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