Question PC powers On/Off in loops - I suspect PSU or motherboard Issue ?

[JMan21]

Hello everyone,

I’ve been troubleshooting a problem with my PC where it powers on for a few seconds and then turns off, only to turn back on again. I’ve done a lot of testing and want to provide all the details to see if anyone can help me figure out what’s going on.

System Specs:​

• Motherboard: ASRock B450 Pro4 (New replacement motherboard from the manufacturer)
• CPU: AMD Ryzen 5 5500
• GPU: NVIDIA GeForce 3050 Low Profile (removed for troubleshooting)
• RAM: Silicon Power Value Gaming DDR4 16GB (1 stick tested, removed other stick for troubleshooting)
• Storage: TEAMGROUP MP33 512GB M.2 SSD
• PSU: Thermaltake 600W
• Case Fans: 6 LED case fans (powered directly from PSU)

Symptoms:​

• PC powers on for a few seconds, then powers off.
• The PSU fans stop spinning as well.
• After turning off, the system attempts to power back on in a loop.
• Everything seems fine when I unplug the 24-pin connector and use the paperclip test (PSU stays on).
• The issue only happens when I connect the 24-pin connector to the motherboard.
• When the motherboard is disconnected, the case fans powered directly from the PSU work fine.

Troubleshooting Steps Taken:​

1. Paperclip Test: I’ve confirmed that the PSU works when I do the paperclip test; it stays on without issues when the 24-pin isn’t connected to the motherboard.
2. Reseating and Checking Connections: Double-checked all power cables (24-pin, CPU power 8-pin).
3. Testing With GPU Removed: I removed the GPU and still had the same issue.
4. Testing With One Stick of RAM: I tried with just one stick of RAM and without the other.
5. Motherboard Outside Case: I took the motherboard out of the case to avoid any potential shorting issues from the case.
6. Powering Fans Directly from PSU: The fans still work without issue when connected directly to the PSU, but the motherboard fails when connected.

What We Think Might Be the Issue:​

• PSU Underperforming: The system seems to work when the motherboard is not connected, suggesting the PSU may not be able to supply enough power to the motherboard and other components under load.
• Motherboard Power Issue: It’s possible the motherboard might have a fault preventing it from drawing stable power, causing the PSU to shut down.
• Power Delivery Issue: Given the system has a Ryzen 5500 and a low-profile GPU, I suspect there might be an issue with how the PSU handles the power load.

What I Don’t Have Access To:​

• I don’t have a spare PSU to test at the moment, which makes me more inclined to think it could be a power issue, but I'm not sure.

Has anyone else encountered a similar issue with a 600W PSU, especially under load with a B450 motherboard, or could this be a motherboard-specific problem? I'd greatly appreciate any advice or suggestions on what else I should try or how to narrow down the issue further!

Thank you in advance for your help!

 

[Lutfij]

Welcome to the forums, newcomer!

PSU: Thermaltake 600W
Thermaltake is the brand of the PSU, while 600W is the advertised wattage of the unit. What is the model and age of the unit?

 

[JMan21]

Welcome to the forums, newcomer!

PSU: Thermaltake 600W
Thermaltake is the brand of the PSU, while 600W is the advertised wattage of the unit. What is the model and age of the unit?

Here is the model it says on amazon "

Thermaltake SMART 600W ATX 12V V2.3/EPS 12V 80 Plus Certified Active PFC Power Supply PS-SPD-0600NPCWUS-W"​