Power Supply Fan Won't Turn Off

[JCO]

Recently a friend brought over his computer because the Power Supply Fan
would continue to run after the computer was shutdown. So I exchanged the
Power Supply, did all security updates, cleaned all Temp files and garbage
from the computer. I also cleaned/compact the Registry and made a backup of
the Registry.

Changing the power supply alone, seemed to do the trick and was the initial
thought. He's had the computer at his house for 3-weeks, then the problem
returned. Unfortunately I threw out the old power supply but now I'm
wondering if this could be a software or motherboard issue.

Any ideas on what would cause the power supply to do this?
Is it logical to think that the motherboard may have an issue and a possible
current spike could be damaging the power supply?
Any thoughts?

 

[Terry]

On 4/10/2007 11:07 AM On a whim, JCO pounded out on the keyboard

Recently a friend brought over his computer because the Power Supply Fan
would continue to run after the computer was shutdown. So I exchanged the
Power Supply, did all security updates, cleaned all Temp files and garbage
from the computer. I also cleaned/compact the Registry and made a backup of
the Registry.

Changing the power supply alone, seemed to do the trick and was the initial
thought. He's had the computer at his house for 3-weeks, then the problem
returned. Unfortunately I threw out the old power supply but now I'm
wondering if this could be a software or motherboard issue.

Any ideas on what would cause the power supply to do this?
Is it logical to think that the motherboard may have an issue and a possible
current spike could be damaging the power supply?
Any thoughts?

An issue of that sort wouldn't be related to Windows, so you can stop
looking there.

I have never seen that except in a laptop that might run the fan a bit
cooling the internal temperature to the required heat range before
shutting down.

I would first check the BIOS to see if there are any settings that may
have been changed regarding power settings, heat ranges/fans, etc. Try
resetting to defaults (unless you have a custom configuration) and see
it that changes.

Report back,

--
Terry

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[John]

Any ideas on what would cause the power supply to do this?
Is it logical to think that the motherboard may have an issue and a
possible current spike could be damaging the power supply?
Any thoughts?

Are you sure that he is doing a shutdown and not a standby?
The power supply stays on when standby is invoked.
Is he running Vista? Standby is the default for Vista RC2.
(I don't have the release version of Vista).

 

[JCO]

I tried it when he brought it over otherwise I would not of believed it
myself. When you do a shutdown, the fan on the power supply continues to
run. I'm thinking some spike is trashing the power supply.

 

[Andy]

Use a meter to measure the voltages at the motherboard ATX power
connector. If the power supply fan is still running, that means that
the power supply is putting out +12 volts, which means that the
motherboard would also be powered.

 

[over]

Some power supplies are designed to do this - the fan runs until the
temperature goes down. Often the temperature control also results in the
fan NOT running after a cold startup until the temperature goes up.

 

[Peter Foldes]

This has happened to a user at one of my customers location. The user went through 3 power supplies before the IT guy found the problem.

The user had his computer below his station under the desk and was blocked on all sides with boxes of paper. The Power Supply did not get any ventilation or none.
They found that after changing the supply the issue stopped only to return in his case in about 2 days.
The power supply has a safety control inside that tells it to run the fan when it gets overheated and even after it is shutdown just like in a car There is a control that controls this inside the supply. If this gets burned out it will always feel that the supply is overheated and will make the unit run continuously even if your power switch is off.

 

[JCO]

Thanks... I will research the environment and see if it ever cools down
enough to shutdown.
Will let you know.

This has happened to a user at one of my customers location. The user went
through 3 power supplies before the IT guy found the problem.

The user had his computer below his station under the desk and was blocked
on all sides with boxes of paper. The Power Supply did not get any
ventilation or none.
They found that after changing the supply the issue stopped only to return
in his case in about 2 days.
The power supply has a safety control inside that tells it to run the fan
when it gets overheated and even after it is shutdown just like in a car
There is a control that controls this inside the supply. If this gets
burned out it will always feel that the supply is overheated and will make
the unit run continuously even if your power switch is off.