PSU -12v pin = -11.25

My desktop PC is freezing randomly, so I decided to test PSU (Power Supply Unit).
I have tested voltages on all of 24 pins of PSU connector and all voltages are fine except on the blue pin.
Blue pin is -12V and I measured -11.25V.
I know that tolerance is +/- 4%, so it should be between -11.52 and -12.48V.
Is PSU bad? Is that the cause of PC freezing?

What exact model and how old ?

What voltages you have on the other terminals ?

Have you tried to see (software) what voltages are at high load ?

Grossel said:

What exact model and how old ?

Click to expand...

It's about 5 years old.

Grossel said:

What voltages you have on the other terminals ?

Click to expand...

All in range.

Grossel said:

Have you tried to see (software) what voltages are at high load ?

Click to expand...

I have tried SpeedFan, but voltages are incorrect.

I would not worry about that voltage. The -12V was used for RS-232 signals and for a few sound cards (add-on sound cards). The -12V is a low current (low power) voltage and used very little now-a-days. It is unregulated, so it can vary a lot depending on the PSU and whatever load is using it, if any.
If all the other voltages are good, the PSU is probably good as well.

The only thing using -12V, if you have it, is RS232 I think, so shouldn't be a problem.

I don't have any RS232 devices.
So, PSU is fine, I have to test other components.

if you have an oscope, check your +5 and +3.3 rails for noise. any more than 50mV of noise is a possible cause of freezing problems.

Sorry, I don't have an oscope.
I still can't determine the cause of freezing, it's been a week since last freezing.
I tested RAM and there are no errors found.
HDD is new.
I think that most likely cause is the motherboard.
Maybe someone from the description of the freezing event can recognize the issue:
First, mouse and keyboard are working, I can move mouse around and click everything, but nothing opens. For example, I can click Notepad icon but it doesn't open.
After couple of minutes computer stops responding, mouse and keyboard aren't working, picture on monitor is freezed.
HDD activity light on the case is on constantly, no blinking.
I have to restart computer at that point.
CPU temp is ok, bellow 50 C.
I checked Events log but nothing is recorded.

with the HDD light on all the time, and no programs opening, sounds like a virus... or the windows swap file is corrupted... a corrupted swap file would likely show up in the event log though... a virus would definitely want to avoid any activity that would show up in the event log... bad hardware should cause things that show up in the event log.

I have Kaspersky antivirus for years, it never detected a virus.
It could be some Windows files corrupted though, but nothing specifically is shown.

To check Windows files, run "SFC /scannow"
It will scan the integrity of the Windows operating system.
Crashes can also happen with bad drivers. Try tapping F8 on Windows startup and try starting in "Safe Mode". If no crashes, likely a driver. If it crashes in that mode, then more likely hardware.