Question PC turns on and off randomly, I have to wiggle the 24-pin connector sometimes ?

[cbsn]

I’ve been experiencing numerous issues with starting my computer. Initially, when I assembled it, the motherboard LED would light up, but nothing would happen when I pressed the power button or attempted to jump-start it. After multiple checks and troubleshooting, I found that jiggling the 24-pin connector seemed to resolve the issue. The computer functioned without any problems for three years, during which I avoided touching the 24-pin ATX connector while cleaning.

Recently, while watching a video, my computer froze unexpectedly and emitted a strange noise through the headset. After unplugging, waiting a few minutes, and replugging the power cable, I noticed that the motherboard LED would turn on and off within a second. A few days later, when I checked again, the LED stayed on and the computer functioned normally.

After cleaning and reassembling everything inside the case, the computer turned on but didn’t display any video output. This issue was resolved by jiggling the 24-pin connector again. The computer worked fine until I opened it to adjust the CPU fan connection, after which it stopped working again. Jiggling the 24-pin connector once more seemed to fix this issue.

The computer functioned well for an entire day, even during gaming sessions. However, on the following day, I had to press the power button three times to start it. On the third day, it wouldn’t turn on at all until I jiggled the 24-pin connector again.

At this point, I attempted to isolate the problem by unplugging it from the wall and pressing down on the power button to drain any residual power. However, this caused the LED to turn on and off within a second after plugging in the power cable again(note it only started happening after I drained the power, and it is happening until now).

Now, if I wait for about five minutes before trying to turn it on(the PSU is off, but still plugged into the wall), it starts up fine. But if I switch off and then immediately switch on the PSU, the LED goes on and off again within a second.

It’s worth noting that after the freeze, when I managed to get it working again, there was no video output even though the case fan was functioning properly. After resolving the video issue, however, the case fan stopped working and hasn’t worked since. It is also worth notting that I already replaced the PSU's fuse, because it opened due to the some problems with the climate(I am pretty sure).

I’ve checked all cables and reseated components multiple times but to no avail. The PSU passed a clip test but doesn’t seem to power up the case fan.

The 24-pin connector doesn’t appear damaged or faulty upon inspection. The motherboard socket also seems fine. The connector is fully inserted with no room left.

Currently, both the motherboard and PSU are outside of the case for isolation purposes. I’ve also disconnected unnecessary connectors and removed the graphics card to rule out any potential issues from these components.

I plan to test the mobo with a new PSU soon to identify which component is causing these issues. But, if anyone has experienced similar problems or has any insights into what might be causing them, I would appreacite so much!
Here are my system specs:

• CPU: Core i5 9400f
• GPU: Gtx 1660ti
• PSU: Gamemax GM 500W
• Motherboard: Asrock fatality b360m performance
• RAM: 2x8gb 2666mhz

Also, below is the link to show a demo of what is happening now. Thanks everyone so much in advance!

View: https://www.youtube.com/watch?v=uy9qXQ0eCyQ

 

[punkncat]

Check to make sure all of the pins in the 24 are firmly forward in the connector (like haven't been pushed back/out).

This sounds like an issue with the caps in the PSU but really a vague guess.

 

[stonecarver]

It is also worth notting that I already replaced the PSU's fuse, because it opened due to the some problems with the climate(I am pretty sure).

Take that power supply out of the mix and test with a loner power supply at the very least.

 

[Misgar]

I make it a rule not to "clean" PCs unecessarily. Each time you pull things apart and apply liberal quantities of compressed air, vacuum cleaner nozzles, soft haired brushes, dusters, Isopropyl Alcohol, etc., you run the risk of ESD damage and mechanical failure.

I do clean my fan filters every 6 months, but otherwise leave things alone until the next upgrade. When I do work on PCs, I place them on an anti-static work mat and wear a wrist strap. No point in zapping sensitive components unnecessarily.

If one of the PSU wires has broken off inside the insulation just above the crimp tag in the 24-way connector, you'll get intermittent connection when you "waggle" the lead. Many wires in the 24-way connector are "doubled up" for extra current, but some wires are on their own, so if you lose one of these, the PC may stop working.

Plugging and unplugging the 24-way connector may eventually lead to loose crimp tags and intermittent connection. It's also vaguely possible the pins in the motherboard connector have dry joints underneath. Either way, try a new PSU and see what happens. Best of luck.

 

[cbsn]

Check to make sure all of the pins in the 24 are firmly forward in the connector (like haven't been pushed back/out).

This sounds like an issue with the caps in the PSU but really a vague guess.

Thank you for your response! It turns out that the problem shown on the video was resolved simply by removing the CMOS. To actually check it, I reinserted it and the problem reappeared. I will replace and put everything back to see if it will work normally or not.

 

[cbsn]

I make it a rule not to "clean" PCs unecessarily. Each time you pull things apart and apply liberal quantities of compressed air, vacuum cleaner nozzles, soft haired brushes, dusters, Isopropyl Alcohol, etc., you run the risk of ESD damage and mechanical failure.

I do clean my fan filters every 6 months, but otherwise leave things alone until the next upgrade. When I do work on PCs, I place them on an anti-static work mat and wear a wrist strap. No point in zapping sensitive components unnecessarily.

If one of the PSU wires has broken off inside the insulation just above the crimp tag in the 24-way connector, you'll get intermittent connection when you "waggle" the lead. Many wires in the 24-way connector are "doubled up" for extra current, but some wires are on their own, so if you lose one of these, the PC may stop working.

Plugging and unplugging the 24-way connector may eventually lead to loose crimp tags and intermittent connection. It's also vaguely possible the pins in the motherboard connector have dry joints underneath. Either way, try a new PSU and see what happens. Best of luck.

Thanks so much for your reply. Actually, I clean it every six months or more(I only removed the 24pin connector only once within 3 years). When I clean, I take off only the necessary parts, like cpu fan. I also make sure to put it on an anti-static mat, gently remove the cables and so on. As I said, I have this problem since I first build it. I will actually try using another PSU to make sure I do not have any broken wire as you mentioned. Also, the problem on the video has been solved by taking the CMOS off.

 

[cbsn]

Update:
I bought a new CMOS, as my computer would only boot and start correctly without the old one... But, It did not solve my problem. I then took it off and turned the pc on, used it for awhile, then flashed the BIOS using the latest version, and.. Voilá, it worked. After that, I did not face any more problems, all of them surgically disappeared, even with the new CMOS on. I put everything back, and it is working untill now.

 

[cbsn]

Being straight, I am having this exact problem since I first built it. The computer simply just does not turn on, even with the mobo led on. I did everything possibly, I just did not test with another PSU, but I am doing it soon. It is now outside the case, with 1 stick of ram, CPU, and the ATX power cabble connected. I try to use a screw driver to make it turn on, but nothing happens. When I built it, I did have the same problem, to solve it, I simply jiggled the atx cabble and used it for 2 years straight and did not face any problems. These days I was facing some similar ones, but I solved the changing the mobo CMOS and upgrading the BIOS. Yesterday, I left the computer in standby and when I came back it simply did want to work, even when I forced it to reboot. I tried everything safe I could, but so far the mobo only turns on if I short the psu with the 24pin atx connector connected to the motherboard. If anyone has any recommendations, I would appreacite so much!