ATX -12V Value

  • Thread starter Thread starter David K.
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David K.

My ATX12V power supply is reporting to the bios a value of -9.07V on
the -12V Rail. The minimum for the ATX spec is -10.80.

Is this what you would consider a problem and would you have it replaced?

Here are the minimums from formfactors.org.

2.2.1 DC Voltage Regulation
The DC output voltages are required to remain within the regulation ranges
shown in
Table 2, when measured at the load end of the output connectors under all
line, load, and
environmental conditions specified in Section 4.
Table 2. DC Output Voltage Regulation
Output Range Min. Nom. Max. Unit
+12V1DC (1) ±5% +11.40 +12.00 +12.60 Volts
+12V2DC (1) ±5% +11.40 +12.00 +12.60 Volts
+5VDC ±5% +4.75 +5.00 +5.25 Volts
+3.3VDC (2) ±5% +3.14 +3.30 +3.47 Volts
-12VDC ±10% -10.80 -12.00 -13.20 Volts
+5VSB ±5% +4.75 +5.00 +5.25 Volts
Note:. (1) At +12 VDC peak loading, regulation at the +12 VDC output can go
to ± 10%.
(2) Voltage tolerance is required at main connector and S-ATA connector (if
used).
 
David said:
My ATX12V power supply is reporting to the bios a value of -9.07V on
the -12V Rail. The minimum for the ATX spec is -10.80.

Is this what you would consider a problem and would you have it replaced?
Click to expand...

Two things:
First I would NOT rely on the CMOS reading to be accurate, use a DVM
to measure the voltage at the PS connector on the MB.
Secondly if I recall correctly, I think the -12 was only used for the
serial port. If you are not using any serial devices, that might
explain it. If there is NO load on the output, the reading could be way
off.
 
My ATX12V power supply is reporting to the bios a value of -9.07V on
the -12V Rail. The minimum for the ATX spec is -10.80.

Is this what you would consider a problem and would you have it replaced?
Click to expand...

The -12V rail isn't used, it is not a problem. There is no need to
replace the power supply because of that, if you feel it's otherwise a
good unit.
 
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