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JeffMD
join:2002-08-16
Edgewater, FL

JeffMD to DanChaos

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Re: PC fan won't shut off

dan is actually right. His acpi driver has failed some how and is not powering down the psu. Remember that the motherboard handles full control on the psu, and while the mother board is free to power down on its own, if the signals don't get to the psu then the psu and fans, drives stay on.

Take a look in your device manager and under the computer tree will be the acpi driver. If one is there try deleting it and rebooting.

DanChaos
Premium Member
join:2006-08-10
Colombia

DanChaos

Premium Member

Thank you JeffMD, I will try that out tonight.
James_C
join:2007-08-03
Florence, KY

James_C to JeffMD

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The motherboard doesn't need ACPI or a driver at all to turn PSU on and off, that's a latching electrical signal from a chip... doesn't even need the CPU and memory installed, which would be required for any driver or bios code to decompress and run.

There are a few reasons why it might not shut off, and probably others I can't think of at the moment.

1) Defective power supply
2) Defective motherboard
3) Motherboard shorting out against case, a case standoff, or some other metal object
4) Front panel connectors plugged in wrong or power switch defective and/or sticking.

However, the way the event was described it is not clear to me whether it is continuing to exhibit this behavior or only did it once.

It may or may not help to have more specifics like make and model of PSU, and of motherboard, where the fan is plugged in on it, and if Dan has a multimeter then to check power supply rail voltages so we know which are live, and to unplug PSU from motherboard, short the PS-On green signal wire to a ground wire to turn it on, then unshort it to confirm it turns off as it should (except for 5VSB power rail).

DanChaos
Premium Member
join:2006-08-10
Colombia

DanChaos

Premium Member

I have not touch the PC lately, but last weekend Windows froze with a blue screen stating that they was a memory dump and that if this issue was repetitive it may be related to new software or hardware installed (I cant remember exactly what the screen said).
This did happend again after I rebooted the PC, so I decided to reinstall windows hoping to fix the problem.
After the new install the system did not crash again, but the non stopping fan problem remains, it wont shut off when I tell windows to turn off.

James from your post, I'm starting to belive that the problem is motherboard related. I just did a back-up of all my files just in case. Is it worth to fix the motherboard? is and old system I bought like 3 year ago (I'm going to look for the model).

Raible
join:2008-01-23
Plainfield, IN

Raible

Member

said by DanChaos:

Is it worth to fix the motherboard?

No.

And like James said, it would be nice if you could tell us more about your machine like what motherboard and PSU you have.
James_C
join:2007-08-03
Florence, KY

James_C to DanChaos

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At that system age I would suspect the power supply is failing, likely something like vented capacitors. If it's out of warranty, pop the PSU casing open -with it unplugged from AC- and inspect it.

This would also be common with the bluescreen errors you're seeing, which aren't related to a latching problem or sticking case switch. Regardless of what the bluescreen stated, it's not likely a software issue although a driver bug can cause bluescreens, and yet it wouldn't also cause the failure to shut down.

Someone competent at motherboard repair might or might not find it cost effective to repair, but someone like that has their time more valuable than the cost of a replacement compatible motherboard.

It could also be that a failing power supply damaged the motherboard so you need both parts. If I had to pick what to do and had no other parts for testing nor another way to acquire them, then what I would do is buy a new power supply from a place with a good return policy so if that doesn't fix it you can seek a refund and then proceed to replace the motherboard, except that as I mentioned above, it is also possible both parts are damaged.

Raible
join:2008-01-23
Plainfield, IN

Raible to DanChaos

Member

to DanChaos
said by DanChaos:

last weekend Windows froze with a blue screen

Oh please please someone read my first post.