PC hot, fans not working

April 29, 2009 at 14:16:55
Specs: Windows XP, 1.70GHz Celeron/1GB
I've got a PC built by a friend in late 2003 that I recently upgraded. I had 1 256MB SDRAM stick and I swapped that out for 2 512MB SDRAM sticks. So, I have the maximum RAM allowed for the motherboard, which is an ECS = P4VXASD2+ Version 5 (a Socket 478 board), which is run by a 1.70 gigahertz Intel Celeron. It seems since that upgrade that the PC has run hot. The walls of the case are hot. Both of the hard drives, a SEAGATE ST3320620A 320GB BARRACUDA ATA100 (set as the main C:) and a Western Digital WD600BB-75CAA0 60.0GB (set as a backup D:), feel hot to the touch. There are four fans inside the case:

1 on the motherboard
1 on the inside rear of the case that is connected to the C: drive and power supply
2 (one internal and one external) on the power supply box.

Here are some photos that show all but the motherboard fan and the "splitter" I mentioned:

The only fan that's working is the one on the motherboard. The others are deader than door nails. I can't figure out why they are working or what I should do. The result is clear, I think: my PC gets hotter than it should.

I would appreciate any suggestions as to how to resolve this problem What could be causing 3 fans to fail to work? Should I replace the fans or something else? They are all connected to the power supply. I don't have any problems turning on and turning off the PC, other than Windows XP hanging up on a blue screen saying "Windows is shutting down...." which I know is an OS issue. The PC doesn't shut down on its own. It will run, but it runs hot. So, again, any suggestions to resolve this issue would be greatly appreciated. Thanks!

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April 29, 2009 at 16:19:10
I would test the psu to is if any of the 12v connections fail.
The one with the psu should start upon powering up the system.

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April 29, 2009 at 17:53:27
With your finger try to spin the fan blades. Do they spin freely with no resistance? If not, they're bad.

Often case fans are procured from old cases or power supplies so they may not have been new when you got them. And it's not likely they failed all at once--you just may not have noticed that one or even 2 had shut down.

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April 29, 2009 at 17:54:33
Thanks for the quick response.

How do I go about doing the testing you suggest? What tools if any will I need? Is there some sort of diagnostic program I can run? Thanks!

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April 29, 2009 at 18:23:16
So the fans are connected to the same 4-wire connections as are the drives? Try connecting the fan power connections to different ones--there's usually spares. Sometimes one of the metal connectors can get flarred out and not make a good connection.

But first spin the blades with your fingers. If they don't spin freely you KNOW the fan is bad and don't have jack around with trying different connections.

Oh, and if the fan(s) that cool the power supply aren't spinning you better get that fixed pretty quick.

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April 29, 2009 at 22:17:38
Try also on Cleaning the Whole tower. The tower must have a tons of dust on it.

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April 30, 2009 at 08:11:16
Thanks for the replies. I appreciate the support.

"With your finger try to spin the fan blades. Do they spin freely with no resistance? If not, they're bad."

I used my finger and/or a pencil/pen to try turning the blades on the fans. I was able to turn the blades without any resistance on 2 of the 3 bad fans, the one on the inside rear and the one inside the power supply. There was slight resistance on the one that's attached to the back of the power supply. What might that indicate?

"So the fans are connected to the same 4-wire connections as are the drives?"

Here are some pics, including a scanned diagram, of my PC fans.


I'll have to try the testing later. I'm not sure how to go about "connecting the fan power connections to different ones." Where would I find those different ones.

I do know how to do the cleaning. There was in fact a lot of dust built up. I went to an office suppy store and bought one of those cans of air to blow out the dust.

Thanks again for all the help!

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April 30, 2009 at 15:42:23
The bearings/bushings most of those fans use aren't very high quality. Add some dust and they start slowing down.

The PSU fans aren't going to be connected externally with the 4-wire molex. Their control should be internal or from the motherboard. Most motherboards will have several 3-pin headers for various fans. You might check and see if one of those is connected to your power supply. If it's connected that way then the bios controls when the fan is on or off. You can usually set it to 'always on' in cmos/bios setup. Or I think if you disconnect that wire then the fans are always on.

If the one in the rear of the case seems to spin OK then it's probably not clogged. Connect it to a different power connector. It should always be on since it has no external control. If it still doesn't work then replace it. Although they usually last until they get clogged they can go bad for no apparent reason.

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April 30, 2009 at 17:14:01
Thanks for the info. I'll check it out as much as I can. However, I think I'm going to take it to the guy who built it for me at have him look at it. I'm concerned now because the desktop blinked on and off like a light at an intersection, especially when I was trying to multitask, such as trying to copy some files from my hard drive to a CD in one of my CD burners. The PC was on and running, but the "picture" on the monitor disappeared and reappeared again. I couldn't move the cursor around, and "ghost images" of the cursor appeared wherever it had last been. The way the PC was acting reminded me of a circuit that's overloaded and flickers on and off. I touched both hard drives, and both were really hot. So, I figured the C: drive (the master with XP loaded) was way too hot and acting up, so I shut the PC down. I didn't want to risk frying the hard drive. I hope it's ok now, though. What do you think?

So, I'm here at my parents house with my external hard drive copying files from it to CDs to make room to copy files from my C: drive to the external hard drive. I don't want to lose my music and such.

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