Question The PC sometimes doesn't turn on at all

[lerizvy]

Hi,

I built a PC two months ago with the following specs:

• Motherboard: MSI B550M Mortar Wifi
• CPU: AMD Ryzen 5 5600X
• Graphics Card: Sapphire Pulse RX Radeon 6700XT
• PSU: BitFenix BFG Gold 750W
• Case: MSI Mag Forge 100M
• RAM: Kingston FURY Beast 16 GB 3200 MHz x2
• SSD: Samsung 970 EVO 500GB NVMe M.2

After a while, I noticed that the CPU LED on the motherboard was on. I researched this and found that others with similar boards reported it as a bug, so I dismissed it since everything seemed to work fine.

Later, when I pressed the power button, sometimes the fans would start, but there would be no display or power to the USB devices. Trying again would usually get it to start and work fine. Now, when I press the power button, sometimes nothing happens at all, while other times it works fine.

Today, I decided to troubleshoot the issue since it wouldn't start again. I began with the CPU because the light on the motherboard was still on. After reseating the CPU, the system booted normally and worked fine, but the CPU LED was still on. To confirm, I powered it off and tried to turn it on again, but it didn't work at all—no fan movement and no lights.

I'm not sure how to proceed with troubleshooting. Could you suggest some steps? For instance, why doesn't it power on after being powered off? Should I investigate the PSU, or is it more likely a motherboard issue?

Thanks!

Update: I tried to turn it on again. At first, it turned on successfully without the CPU LED on, which I think is the first time in a while. Then I restarted it and it got stuck at the beginning: only the fans were working and the CPU LED was on, but USB devices and the display didn’t get a signal. I restarted again, and this time it didn't turn on at all. This is a similar pattern to the other occurrences.

Update 2: I replugged the power button cables, and it turned on without issue. I also disabled fast startup. It might be a combined issue of these two things.

Update 3: After waiting for a while, it started without an issue. However, when I powered it off, it didn't start again. To eliminate the case, I tried to jump start the motherboard, but it didn't work. So, I guess the issue is either with the PSU or the motherboard.

Update 4: I swapped the PSU, removed the GPU and RAM, but the issue is still there. It powers on sometimes if I unplug everything and then reconnect it to the power. However, if I shut it down, it doesn't respond to the power button. So, I guess the issue is with the motherboard.

 

[Ralston18]

Power down, unplug, open the case.

Clean out dust and debris (hopefully little or none).

Verify by sight and feel that all connectors, cards, RAM, jumpers, and case connections are fully and firmly in place.

My thought being that some original connection seemed tight when you first built the PC. No one wants to force anything (especially with a new build) so what may have seemed tight actually was/is not tight. And over the last couple of months has loosened up bit. Intermittent connectivity until the system warms up a bit.

Unplug and replug all connectors, jumpers etc. a few times. Reseat all cards and RAM. Leave the CPU alone.

Something may suddenly go much more smoothly back into place and feel much more secure.

 

[lerizvy]

So, it worked fine the day I wrote the last update, but the next morning it didn't turn on. I unplugged the JFP1 cables and replugged them, and it worked and turned on. I wanted to test it again, so I powered it down, but when I pressed the power button again, it didn't react. So, I followed the suggestion: I unplugged everything and replugged them. It turned on but couldn't boot or power the USB peripherals. I powered it down and pressed the power button again, and it didn't react, again.

The pattern is pretty similar every time, and I still can't figure out how to troubleshoot the issue. I have another build with similar components, so I might try switching some parts to see if it has any effect, but it would be a tedious process since I have to deconstruct two builds. Do you have any reasonable suggestions for troubleshooting it piece by piece?

(Updated the original post)