Power supply fan starts and stops, why?
March 19, 2012 11:13 AM   Subscribe

The fan in the power supply on my PC has been briefly cutting out, about once every 30 seconds. This makes the sound kind of annoying. Do I need to replace the entire power supply or can I just replace the fan?

I'm not sure if I can just blame the fan, or if it's a symptom that the power supply is on the fritz. If the former, replacing the fan should do it.

I'm also tempted to slap a case fan in there and plug it into one of the case fan connectors on the motherboard. (This still requires I buy a new fan, since the power supply fan is 2-pin and the case fans are 4-pin) Would that be a terrible idea, since its speed would no longer be controlled by the power supply temperature?
posted by RobotHero to Computers & Internet (17 answers total) 1 user marked this as a favorite
I'm going to assume you don't have the tools to test the fan once you got it out of there. If you do and if it's clearly a modular power supply -- god knows what they're soldering to what in Dells and HPs these days -- just test the fan and see what happens.

Otherwise, unless you've got some sort of fancy custom rig, a new power supply fan is five bucks. If (if) you know what you're doing, just replace the fan. Worst case scenario you're out the cost of a power supply plus five dollars.
posted by griphus at 11:31 AM on March 19, 2012 [1 favorite]

It's probably just the fan. The fan cutting out usually doesn't have a whole lot to do with the power supply dying, it's just a moving part and those always go first (see also: printers).

On the other hand, a power supply running with no fan could end up damaging itself. I'd spend the money (5 bucks?) on a new PS fan and not do the case fan thing.
posted by Feel the beat of the rhythm of the night at 11:31 AM on March 19, 2012 [1 favorite]

(Well, worst case scenario is that you somehow manage to fry your PC, but if you're genuinely worried about doing that, just get a new power supply or have a friend help.)
posted by griphus at 11:32 AM on March 19, 2012

Power supplies are fairly inexpensive. It's probably not worth the hassle of rigging a fan-only replacement when just swapping the power supply is so easy and low-cost.
posted by axiom at 11:35 AM on March 19, 2012

The fans in PSU's are largely standard fans. Do understand that opening the PSU is 1. dangerous, those capacitors can carry a hell of a shock, and 2. breaks any and all warranty. If the PSU is still under warranty (can vary from 1 to 7 years depending on manufacturer) then get it replaced. If it's out of warranty, I'd personally just replace the whole PSU.
posted by Mister Fabulous at 11:37 AM on March 19, 2012 [3 favorites]

You know how I qualified my answer with an "if"? Well, I've got a pretty good litmus test for you:

Do understand that opening the PSU is 1. dangerous, those capacitors can carry a hell of a shock...

If your mental response was anything short of "no shit, Sherlock" you may want to just replace the whole power supply.
posted by griphus at 11:44 AM on March 19, 2012 [2 favorites]

Replace the whole power supply.
posted by caclwmr4 at 11:46 AM on March 19, 2012

A decent desktop power supply can be had for less and $40 US. I'd just replace it. The capacitors in a PSU are pretty dangerous if you're not used to higher voltage components.
posted by bonehead at 11:46 AM on March 19, 2012 [1 favorite]

Best answer: Yeah, I would just put a whole new one in. Check to see if it's still under warranty though... should be 1 year.
posted by jeffamaphone at 12:01 PM on March 19, 2012

Also... could the fan be dirty? I've noticed computer fans that get too much dust in them start to run wonky.

Nthing "Careful with that power supply!"
posted by luckynerd at 12:01 PM on March 19, 2012

Response by poster: Warranty is 1 year, I've had it for 1 year and 3 months. :(

I already had it open, that's the only reason I know the fan has a 2-pin connector.

I guess I'll replace the whole unit, it's just I haven't had one conk out on me so soon.
posted by RobotHero at 12:56 PM on March 19, 2012

I have. I keep buying slightly more expensive ones hoping the next one will be the one that lasts.
posted by jeffamaphone at 1:15 PM on March 19, 2012

Opening your power supply is dangerous. However, if you are comfortable opening your power supply, and now know what type of fan it has, then yeah, just order one of em, and slap it back in.

Back when I was in high school I used to do this all the time. Actually I would take the little sticker off the center of the fan, pop open the little plastic button underneath, put wd40 inside the middle, spin the fan a couple of times, and reassemble the whole thing. It sometimes helped, but don't do that. Buy a new fan, they are pretty cheap.

And once again, please try to not electrocute yourself. I never had any issues with this as a reckless teenage case opener, but those capacitors are, as others have mentioned, very large. No matter how long your computer has been unplugged, assume that they are fully charged and ready to shock you.
posted by Phredward at 2:47 PM on March 19, 2012 [1 favorite]

There could be a chance that the soldering job sucked on the power supply. But still, it's dangerous to mess around with and your life is worth more than the price of a power supply!
posted by luckynerd at 5:13 PM on March 19, 2012

WD-40 is more solvent than lubricant. It may work in the short term but in the long run that is not a good solution.
posted by jeffamaphone at 8:15 AM on March 20, 2012

Response by poster: I have replaced the powersupply with a new quieter one that has a 5 year warranty.

And for the tangent, on another computer I lubricated the CPU fan with a couple drops of bike chain oil, which is still a very kludgy thing to do but (it think) is more likely to work than WD-40.
posted by RobotHero at 6:12 PM on March 20, 2012

Bike chain oil is not quite as bad as WD-40 for lubricating your cpu fan but it is still far to heavy duty and low rpm for a small fan. I would suggest using regular machine oil like 3 in 1, or sewing machine oil, which are lighter and intended for high rpm. And safer for plastic bits.
posted by zenon at 10:17 AM on March 27, 2012

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