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DanChaos
Premium
join:2006-08-10
Colombia

PC fan won't shut off

Last week windows 7 installed and update, after finishing the update the PC shut off but the fan kept working. (I believe the pc was off because there was no video on the monitor and the green led from the CPU was off).
The only way to stop the fan from working was to pull the electrical cord of the CPU, as soon as I reconnect the CPU the fan starts working again, but the pc will only start when I press the button ON-OFF button of the CPU.

I don’t know if its related with the software update or if there-s something wrong with the mother board or something.

Thanks for the help!.


Dissembled

join:2008-01-23
Indianapolis, IN
Not to be a smartass, but how could it be a software issue if your machine is turned off?

You need to go through all the connectors from your PSU and assure they are in the proper location and are all seated fully. Then, give your PSU a good visual inspection.

If it is still doing it after that, you may be looking at a PSU issue. Live with it, unplug your machine when you turn it off, leave your machine on, buy a new PSU or try and do the electrical troubleshooting yourself.

This may be harbinger of more PSU issues to come. Bring on the BSODs.


sbconslt

join:2009-07-28
Los Angeles, CA
reply to DanChaos
Reset BIOS defaults, possibly.


Krisnatharok
Caveat Emptor
Premium
join:2009-02-11
Earth Orbit
kudos:12
reply to DanChaos
You pull an electrical cord out of the CPU? o.O


JeffMD

join:2002-08-16
Edgewater, FL
kudos:1
reply to DanChaos
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.


Gordo74
Premium
join:2003-10-28
Monroeville, PA
reply to Krisnatharok
said by Krisnatharok:

You pull an electrical cord out of the CPU? o.O

I think by CPU he means tower and by electrical cord from the CPU he means the fan header on the motherboard.


DanChaos
Premium
join:2006-08-10
Colombia
reply to JeffMD
Thank you JeffMD, I will try that out tonight.


DanChaos
Premium
join:2006-08-10
Colombia
reply to Gordo74
yes that what I meant

James_C

join:2007-08-03
Florence, KY
reply to JeffMD
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
join:2006-08-10
Colombia
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).


Dissembled

join:2008-01-23
Indianapolis, IN
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
reply to DanChaos
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.


Dissembled

join:2008-01-23
Indianapolis, IN
reply to DanChaos
said by DanChaos:

last weekend Windows froze with a blue screen

Oh please please someone read my first post.


asdfdfdfdf

@myvzw.com
reply to DanChaos
When it behaves like that you can't get it to shut off completely even if you press AND HOLD the on/off button on your case for 5 seconds?