A weird PSU case study: Seasonic Prime

[knightsljx]

I have a weird situation that I can't explain, so I'm hoping there would be some experts here that could help me solve the issue.

My system was working fine and I decided to update my motherboard BIOS which had a patch for the recent Intel security issue. After the update completed, my system shutdown completely instead of doing a restart as what a normal BIOS update should do. Afterwards, my system could not be powered on at all. No response, no lights, no fan when the power button is pressed.

Long story short, after 2 days of troubleshooting and running around, I isolated the problem to my Seasonic Prime PSU. Somehow it can no longer be powered up immediately upon shutdown. I must power off it and rest for 5 minutes before it will work again. I isolated the issue with a spare PSU which had no issues.

Then I replicated the problem using a PSU tester. When I turned off the tester while it was working, it could not be immediately powered back up. I need to switch off and let it rest again. But in the PSU tester's case, the rest period was almost instant.

Could anyone explain

1) How a BIOS update could do such a thing to a PSU?

2) What is causing the PSU to behave in such a way? shorted caps? Coils?

Thank you.

 

[n0ns3ns3]

That's really weird issue.
What happens if you choose Restart option from OS or if you press reset button on your case ?
Do you have a chance to test it with other MB ?
What is you MB model ?
It's really hard to cause such issue with BIOS, but I'd probably blame the MB. I'd try to reflash the BIOS and set it to defaults.

 

[geofelt]

Your psu has a very long warranty so you are covered.
You should probably contact Seasonic.
PSU and motherboard vendors are very much into reducing power.

1) I suspect that the Bios update has also done something with reducing power off standby voltage that the Seasonic can not handle.
Even when powered off, there is residual power to the cpu which allows it to start up.
The resting delay is probably needed to let residual power totally dissipate.

2) It is not clear to me how to fix this.
But, look into the bios options for power.
There may be some sort of standby setting needed.
What is your motherboard?
You might contact them about this situation.
Or, contact Seasonic with your particulars.
I would have no reason to think the Seasonic is in any way defective.

 

[knightsljx]

My motherboard is the ASUS Z270 TUF Mark 2

I have taken a video of replicating the problem with a PSU tester

https://youtu.be/uh9Bm1qGefQ

I will definitely be sending the unit in. But I just hope to gain some insight why this could happen and prevent a repeat

 

[knightsljx]

That's really weird issue.
What happens if you choose Restart option from OS or if you press reset button on your case ?
Do you have a chance to test it with other MB ?
What is you MB model ?
It's really hard to cause such issue with BIOS, but I'd probably blame the MB. I'd try to reflash the BIOS and set it to defaults.

rolling back the BIOS was one of the many things I tried but didn't solve the problem. It's a very long story of the different combinations of things i tried. which is why i summarised the issue

Restart from OS or reset button does not cause the issue. Only shutting down

 

[geofelt]

If you are on windows 10, shutting down via the windows button does not truly shut down the pc.
Current windows settings are retained.
There is residual power still available as demonstrated in your video.

I think this is to allow windows to do some updates when the pc is not attended.
I have found that holding down the shift key while shutting down does fully shut down the pc.

Before sending in the psu for replacement, I would start a dialog with Seasonic and ASUS.
After all, all was working before the bios update.

If you simply sent it in for a rma, I think you would get a return with exactly the same problem. They may in conjunction with ASUS have a solution.
I think it realis likely to be an issue with asus not 100% adhering to modern PSU specs.

 

[dennis.zuniga]

I have a weird situation that I can't explain, so I'm hoping there would be some experts here that could help me solve the issue.

My system was working fine and I decided to update my motherboard BIOS which had a patch for the recent Intel security issue. After the update completed, my system shutdown completely instead of doing a restart as what a normal BIOS update should do. Afterwards, my system could not be powered on at all. No response, no lights, no fan when the power button is pressed.

Long story short, after 2 days of troubleshooting and running around, I isolated the problem to my Seasonic Prime PSU. Somehow it can no longer be powered up immediately upon shutdown. I must power off it and rest for 5 minutes before it will work again. I isolated the issue with a spare PSU which had no issues.

Then I replicated the problem using a PSU tester. When I turned off the tester while it was working, it could not be immediately powered back up. I need to switch off and let it rest again. But in the PSU tester's case, the rest period was almost instant.

Could anyone explain

1) How a BIOS update could do such a thing to a PSU?

2) What is causing the PSU to behave in such a way? shorted caps? Coils?

Thank you.

I have exactly the same issue that I could not fix. specs:
- seasonic prime gold 850 watts
- asus maximus ix formula
- zotac 1080ti amp extreme sli

after shutdown and I try to press the power button, the lights on the board will will flicker and nothing will happen. have to turn off from the psu and wait for video card light indicator to turn off, power on the psu and boot the machine.