[SOLVED] Is my fan busted?

Nov 15, 2018
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Hello Tom's Hardware.

A few weeks ago, I noticed that my tower would occasionally make a worrysome sound that to me sounds like "gasping for air". One of the fans will for two or three seconds make an almost extreme exhaling sound like it's trying to cool down a component in bursts. I really don't have any better way of explaining this sound.

At first, it only happened on startup and very very rarely after the computer was up and running. Since I'm an idiot and I smoke inside, it's not a mystery to me when a fan needs a good cleaning, so yesterday I cracked it open and went through every single fan, cleaned them up and expected the issue to pass, but now the sound is almost constant, it comes about every thirty seconds, sometimes more.

I am constantly monitoring the temperatures through 'Speccy' and because I never trust software like that 100%, I physically check the temperature too and the temperature fell a few degrees in average after the cleaning, but even before that there was no reason to worry based on the temperature or CPU useage alone.

My detective work has brought me to the conclusion that the fan affected is the fan inside the power source box.

I'm not a genius when it comes to computer hardware, so please cuddle your answers if possible.

Thank you in advance.
 
Replacing the fan inside a PSU is not difficult IF you really understand the risks involved (electrical shock that can be dangerous or even fatal!) AND how to minimize and avoid them. Then, of course, you need some small skills in electrical devices to custom-solder new connections on the replacement fan. Most such fans are simply the same as common computer case ventilation fans - Air Flow designs, not Static Pressure designs. The connections normally are only of the "2-pin" variety - Black wire for Ground, Red wire for +12 VDC, and no connection to a Yellow wire from the fan motor if there is one. Most do NOT need a 4-pin PWM fan type. So IF you feel competent to do this, it can be done. I"ve done this job a couple of times.

BEFORE getting into that, though, consider these points.
1. What you observe may be normal. Many PSU's do their own temperature control of themselves by changing their fan's speed based on a temperature sensor inside the PSU. I have never heard of any that let the mobo do this job for them. Nor is there any way for that internal CPU temperature to be sent outside. So, NO software tool will tell you that PSU internal temperature or the PSU fan's speed. And the CPU and mobo temperature sensors have nothing to do with the PSU's internal work.
2. Slow changes in your workload pattern OR changes in air flow / dust accumulation OR wear of the fan over time may actually mean that the interior of your PSU is now operating at slightly higher temperatures than it used to. Speed of the fan is usually altered in steps according to measured temperature, and not on a smooth scale. So you may simply be in the situation where the PSU internal temperature now is close to a point where the speed control circuit causes the fan to jump up to the next level. But that cools it down so that it falls back, and the process continues to cycle like that. This itself is NOT a problem, other than the annoyance factor.
3. It is also possible that you are seeing the early signs of fan bearing wear. As a fan ages the bearings wear out and the clearance in them gets larger. The early signs of that typically are that, after the system has been off for a while and cools down, at start-up time the bearing clearance is large enough that the fan rotor "rattles" for a short time making noise for less than a minute. During that period the parts heat up and shrink the clearance, and the noise stops and stays stopped while you continue normal use. At a later stage the noise may not stay stopped - it may come and go as you work. Late in the process the noise will be there almost all the time, and certainly will be worse when the fan runs faster. When it gets to that stage, THAT is when you need to replace the fan. Because the next stage is total failure when the fan seizes up and cannot do any cooling at all.
 
Just an FYI: A better free program for temps, fan speed, and component specs is called HWmoniter. Pretty easy to use and it is accurate. https://www.cpuid.com/softwares/hwmonitor.html
Power Supply fans are not really user serviceable since the components inside can carry lethal shocks. I have opened an old power supply and taken the fan out, however, the fan was soldered in with no safe way to disconnect it, making a replacement after I cut the wires difficult. First, Make sure you have cleaned the power supply fan very thoroughly. The best solution, in this case, is to replace the PSU. Can you find a part number on the power supply? It should be displayed on a sticker on the side of the PSU. You should just need to open the side panel to the computer case to see this.
 
Nov 15, 2018
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Hello Remix.

I'll take a look at that application.

I already opened up the power supply itself and took out the power supply fan and you are correct in that it wasn't an easy tax and when I first cracked the seal that warranted about the loss of warranty, I did almost regret doing so. I can find the information if it will help, all I need is to set aside half an hour to crack open the tower again. I was hoping for a definite solution before I open it up again. I do know my way around the inside of my tower, but not to the extend that I want to experiment too much.

 
Unfortunately, there is no definite answer. Once I get that model number I can potentially help you out. Is your computer a small pc or a normal size tower? The chances are the warranty had expired, however how old is this system.
 
Replacing the fan inside a PSU is not difficult IF you really understand the risks involved (electrical shock that can be dangerous or even fatal!) AND how to minimize and avoid them. Then, of course, you need some small skills in electrical devices to custom-solder new connections on the replacement fan. Most such fans are simply the same as common computer case ventilation fans - Air Flow designs, not Static Pressure designs. The connections normally are only of the "2-pin" variety - Black wire for Ground, Red wire for +12 VDC, and no connection to a Yellow wire from the fan motor if there is one. Most do NOT need a 4-pin PWM fan type. So IF you feel competent to do this, it can be done. I"ve done this job a couple of times.

BEFORE getting into that, though, consider these points.
1. What you observe may be normal. Many PSU's do their own temperature control of themselves by changing their fan's speed based on a temperature sensor inside the PSU. I have never heard of any that let the mobo do this job for them. Nor is there any way for that internal CPU temperature to be sent outside. So, NO software tool will tell you that PSU internal temperature or the PSU fan's speed. And the CPU and mobo temperature sensors have nothing to do with the PSU's internal work.
2. Slow changes in your workload pattern OR changes in air flow / dust accumulation OR wear of the fan over time may actually mean that the interior of your PSU is now operating at slightly higher temperatures than it used to. Speed of the fan is usually altered in steps according to measured temperature, and not on a smooth scale. So you may simply be in the situation where the PSU internal temperature now is close to a point where the speed control circuit causes the fan to jump up to the next level. But that cools it down so that it falls back, and the process continues to cycle like that. This itself is NOT a problem, other than the annoyance factor.
3. It is also possible that you are seeing the early signs of fan bearing wear. As a fan ages the bearings wear out and the clearance in them gets larger. The early signs of that typically are that, after the system has been off for a while and cools down, at start-up time the bearing clearance is large enough that the fan rotor "rattles" for a short time making noise for less than a minute. During that period the parts heat up and shrink the clearance, and the noise stops and stays stopped while you continue normal use. At a later stage the noise may not stay stopped - it may come and go as you work. Late in the process the noise will be there almost all the time, and certainly will be worse when the fan runs faster. When it gets to that stage, THAT is when you need to replace the fan. Because the next stage is total failure when the fan seizes up and cannot do any cooling at all.
 
Nov 15, 2018
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Thank you both for your replies.

I'm hella busy right now preparing for a calculus exam, so I probably won't find the time to open it up until tomorrow.

It sounds like we're on the same page, but there's still something about the sound that worries me. I'll try to record the sound and upload it to soundcloud or something like that.

And since you both mentioned the risk factor in opening the power supply and both even implied fatal consequences, I feel pretty stupid as I already cracked it open and took the fan out (without having the slightest clue, I didn't think there was any risk at all given that it wasn't connected to a power socket). By doing so, I deliberately killed the warranty.

I'll get back to you when I find a time to crack it open again.
 
Yes, what you did voided the warranty, but it may have expired already anyway. Depends how old.

Obviously when you start on something like this you disconnect from the wall, which you did. The hazard lurking inside is capacitors. They can store a big charge for a long time, so it is possible you could touch a "hot" point even though it is disconnected. However, if you disassembled it and then left it disconnected and in pieces, it is VERY likely that all residual charges in capacitors have leaked away over the last few days.

Regarding fan size, the size specified is measured as the length on one side of the outside of the fan square chassis. It is not the diameter of the fan itself.
 
Just wear a pair of insulating gloves (not latex) when working. Also if you can, work with one hand to prevent current from passing from hand to hand, through your heart. You will be fine, just don't fool around and take precautions.
 
Interesting post. That hint about working only with one hand to prevent across-the-chest current flow is an old trick from people who serviced tube-type electronic circuits, where voltages normally ranged from 50 V to 500 V, and electrical shocks really were a significant threat of fatality. (Even 40 to 50 VDC across a chest can cause a current flow high enough to disrupt heart function.) Such servicing operations often were done on live circuits to find faults. It has been for used a long time also by some electricians, although among the latter they almost ALWAYS practice complete disconnection and isolation from power sources where possible.
 

I heard of that trick from a guy working on the analog board and CRT in an old Apple computer, so that explains that. I get scared working with any voltage above 12v, although as they always say, it's the amps that kill you, not the voltage. That's pretty much the principle behind tasers anyhow.
 

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