Question Abnormal behaviour of sleep, shutdown and powered-off states on my PC ?

Oct 5, 2024
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I've been observing weird behavior in the last 2 months of my 4yo self-built Ryzen PC.

I've uploaded 2 Videos on YouTube showcasing the problem,

When powering ON the PSU (Scenario-1)

When shutting down the PC (Scenario-2)

In Scenario-1, at 0:08 seconds of the video, as I turn on the switch, the hdd/system activity LED & EZ Debug LED (showing CPU fault) on my MoBo turns ON and remains ON until I press the power button on the cabinet to turn ON the system itself.

In Scenario-2, as I shutdown the PC, at 0:06 seconds of the video, power button light turns OFF as intended but hdd/system activity LED turns ON and remains ON along with all the System fans running at a constant speed until power switch for the PSU is toggled OFF.

Is my PSU at fault? Or is the Motherboard? I've a gut feeling that my PSU is showing these signs of failure. Please help me troubleshoot this issue, PC runs fine as it is, but my usage has been sparse since I've also got a gaming laptop with me.

PC Specs
MBD: MSI B550 Tomahawk
CPU: AMD Ryzen 5 3600
GPU: Nvidia GT 710
RAM: Crucial Ballistix 32GB (16GB x 2) 3600MHz CL16
PSU: Gigabyte B700H 700W
 
Oct 5, 2024
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Refer to the Motherboards User Guide/Manual and double check the case/front panel connections.

It is very easy to get the connections mixed up.

This Motherboard?

https://download.msi.com/archive/mnu_exe/mb/MPGB550GAMINGPLUS_EN.pdf

Verify that I found the appliable User Manual.

Front Panel connections are presented on physically numbered Page 33.
This motherboard -> https://download.msi.com/archive/mnu_exe/mb/MAGB550TOMAHAWK.pdf

I've double checked the connections of my case's front panel IO and switches with Motherboard and they're all okay.

I haven't touched them at all since 2020, this issue started happening recently. I redid the power ON and OFF test got the same result :(
 
Oct 5, 2024
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Install a fresh CMOS battery per the User Guide/Manual instructions for doing so.

Do you have a multimeter and know how to use it? Or know someone who does?

FYI:

https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

PSU is not under load: however, any voltages out of spec would make the PSU very suspect.
Bought a new CMOS battery and installed it, got the same result.

As for multimeter, Yes I do know how to use it, will have to borrow one of those from my workplace tomorrow.

Will report you later with the values :)
 
Oct 5, 2024
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@Ralston18 I think we've caught something here very strange with this PSU haha

Voltages measured below with GND probe at Pin 24 when PSU wasn't powered ON,
Pin 10V
Pin 20V
Pin 40V
Pin 60V
Pin 95V
Pin 100V
Pin 110V
Pin 120V
Pin 130V
Pin 140V
Pin 210V
Pin 220V
Pin 230V

Voltages measured below with GND probe at Pin 24 when PSU was powered ON,

Pin 13.39V
Pin 23.39V
Pin 45.05V
Pin 65.06V
Pin 95.05V
Pin 1012.03V
Pin 1112.03V
Pin 123.39V
Pin 133.39V
Pin 14-11.53V
Pin 215.06V
Pin 225.06V
Pin 235.06V

What I found really interesting were the observations listed down with voltages measured as I turn on the PSU's toggle switch at the back, but didn't power ON the PSU
+ve probe-ve probeVolts
Pin 2Pin 183.38V
Pin 1Pin 173.34V decreasing down to 1.7V gradually
Pin 13Pin 183.34V
Pin 4Pin 182.75V decreasing down to 1.7V gradually
Pin 11Pin 1814.34V decreasing down to 0.1V gradually

This isn't supposed to happen according to Section 4.1.3.1 of ATX Spec as per my understanding.
Video recorded during measurement
Looking forward to your opinion, hopefully my formatting of texts and table here are clear so that anyone easily understand.
 

Ralston18

Titan
Moderator
I do not remember seeing the voltages decrease as you observed.

Not sure about what is happening with those gradual discharges but you may be seeing some capacitor discharging....

That said, lets' double check the process:

Did you disconnect all connectors? Red wire in video is at Pin 24 (COM) - correct?

Noted that 5 volts on Pin 9 - standby ( SB) voltage per the Lifewire link.

And you are using/referencing the voltage specs provided on physically numbered Page 20 of the ATX spec - correct?

Measure via the connectors as shown in the Lifewire link. I could not see a jumper wire - Pins 15 and 16 (Step 5) in the video.
 
Oct 5, 2024
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Did you disconnect all connectors?
Yes.

Red wire in video is at Pin 24 (COM) - correct?
No, that was the Pin 1 (+3.3v).
Red wire is positive probe of my multimeter and while recording the video I was measuring Pin 1 (+3.3v) with respect to Pin 17 (COM)

And you are using/referencing the voltage specs provided on physically numbered Page 20 of the ATX spec - correct?
Correct

Measure via the connectors as shown in the Lifewire link. I could not see a jumper wire - Pins 15 and 16 (Step 5) in the video.
Values with jumper wire connected are listed on the 2nd table of my post above (where Pin 14 is reading -11.53 volts)

My video was meant to show the issue that when I don't connect the jumper wire between Pins 15 and 16, I am effectively not providing PS_ON (Power Supply On) command -correct?

Now, as soon as I turn on the PSU's switch, there's some voltage being measured on Pins as listed on 3rd table , which wasn't supposed to happen in my opinion as my PSU wasn't in the ON state. I hope I was clear 😅
 

Ralston18

Titan
Moderator
Not sure. Proverbial "apples and oranges" territory...

Do some research/"googling" targeting Standby Voltage.

For example:

https://www.techspot.com/article/1967-anatomy-psu/

Many devices that are turned "off" still have power at the ready to ensure a quicker/faster start up.

Likely indicated by some LED.

Some consider a "stand by configuration" as being a waste of energy. Will set that discussion aside.

Key is to find out /discover what is happening in your environment.

If turning on the PSU switch results in some voltage being present that should not be present then the PSU is suspect.
 

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