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Power Supply testing

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Last response: in Components
November 4, 2011 10:33:21 PM

Can I test a computer power supply while it is operating in a running machine? I want to place multimeter probes into the backside (the wire side)of the 24-pin plug while the computer is running. Is this OK to do? I mean will it cause any kind of problem by testing it in this fashion. I have my own subtle reasons for trying this.
Thank you.

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a c 877 ) Power supply
November 4, 2011 11:00:38 PM

If you are just testing voltages you can check the 5volts and 12 volts in a spare molex, easier than going in the main connector (which should be fine).
November 4, 2011 11:14:50 PM

rolli59 said:
If you are just testing voltages you can check the 5volts and 12 volts in a spare molex, easier than going in the main connector (which should be fine).

Thank you for your quick response.
I just wanted to be sure that there was no danger to the computer/power supply by testing it in this fashion.

I keep getting high voltage readings from the BIOS as well a several third-party utilities.
I have therefore changed out the PSU for a new one and I still get the SAME EXACT high voltage numbers I did from the old supply. Such as +12v = 16.34V and +5V = 6.45V, etc.

The computer has been getting these values for over 3-weeks but all seems to be running in fine order. I changed out the PSU because I assumed that the high voltage data I was receiving was accurate.
Now however, with a new supply installed, I am beginning to wonder if the information being sent to the BIOS (and the third-part utilities) is accurate.

Is there something built into the MB that could be causing these voltage to be TRULY as high as the results being reported? Or am I just dealing with bad sensors?

Thanks again.
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a c 877 ) Power supply
November 5, 2011 12:13:05 AM

I would believe bad sensors!
November 5, 2011 12:34:36 AM

rolli59 said:
I would believe bad sensors!

Ok. I tend to agree with you.
But I was reading about the voltage regulators on the motherboard so naturally I began to wonder if these could be the culprit.
I guess what really confused me was the fact that the out-of-wack voltage values I am receiving are GREATER and not LESS THEN the expected output.
I mean, how does a PSU give out more voltage then it is designed to output??
I could understand if it were lower. Then perhaps it was the PSU itself or maybe these voltage regulators on the MB. But HIGHER makes no sense to me.
That is why I am heavily leaning on the sensors to be wrong.

What is your opinion regarding the voltage regulator on the MB? Could it allow for HIGHER voltages then 12V?
Thanks again for your assistance.

a c 140 ) Power supply
November 5, 2011 12:37:27 AM

Probably bad sensors but your on the right track on testing.
November 15, 2011 5:30:47 AM

Tested the system hot; volt meter probes into the wire side of the 24-pin plug.
All voltages were within specs.
BIOS and all third-party utilities gave excessively high readins.
I no longer believe the output.
i'm going bad sensors.
system runs cool (IR gun) and stable.
Bahh...humbug to sensors!
Thanks to everyone for all the assistance.
November 22, 2011 1:10:41 AM

Best answer selected by omicron100.