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I have a cheap 450W PSU with an exhaust fan at the rear. This fan, however, is very loud.

Is it a good idea to replace the stock PSU fan with a quiet fan with similar airflow? The PSU fan is hard-wired to the PCB in the PSU so I was intending on snipping the stock fan wires and sealing the loose ends with electrical tape. I would then connect the new quiet fan to the PWR_FAN socket on the motherboard.

Has anyone done this before themselves? Is it a good idea in the first place? Considering if my PSU fails, it could take out a couple of other components too.

3
  • Please specify your PSU.
    – MicTech
    Jul 20, 2009 at 8:45
  • I'm pretty sure it's a generic manufacturer. I will check next time I can.
    – GaryJL
    Jul 20, 2009 at 9:15
  • @Gary, I prefer heatshrink over electrical tape. Not as easy to find, but electrical tape tends to slide or unwind over time. Also, if you have no pets you can remove try removing the fan grill as I've found that does generate some noise.
    – hyperslug
    Aug 14, 2009 at 4:37

6 Answers 6

15

I have done this. It works.

If you're nervous around capacitors, be aware that they can and will store residual mains power. Practice basic safety: Unplug the psu, ground yourself against the case. Snip the wires, strip them, and use a 'decent' wire splicing method. wrapping them with electrical tape is not a good idea. Solder + heat shrink, small wirenuts, "B-connectors", etc.

I've been hit by the caps, you feel it, but it wasn't horrible. As always, proceed at your own risk, but I've done this plenty of times.

I wouldn't recommend fiddling with the rest of the components, but just a simple wiresnip on the fan leads is pretty painless.

Caveat: Some PSU's run their fan on 12V, some on 5V. If you have a multimeter, check and make sure you pick a fan rated for those speeds. Most 5V 'can' run on 12V, but it's not recommended.

4
  • 1
    It's possible, and the one's I've disassembled all had 80mm fans in them. You should have some basic electronics experience like described in this response. If you don't have any electronics experience maybe you can find someone who does to help you with this.
    – Bratch
    Aug 14, 2009 at 4:15
  • +1 I've done it more than a few times with no issue, although I avoid splicing when I can.
    – hyperslug
    Aug 14, 2009 at 4:31
  • 1
    Plenty of experience of fiddling with electronics! I was more concerned with the long term survivability of my PSU.
    – GaryJL
    Aug 14, 2009 at 8:07
  • 2
    as long as you replace the fan with a comperable one, and don't somehow short/damage things on the main pcb, the electrical scheme is unchanged. No worries bud! On a side note, if you arn't running a decent name brand, consider an upgrade soon. PC stability and longevity depend a lot on the quality of the PSU.
    – Keck
    Aug 14, 2009 at 13:31
6

No, in my opinion opening the PSU is NOT something you should do.

If you do anything wrong the best case scenario is that you only destroy your computer.

The worst case is that it catches fire and you burn down your house and killing everyone in it.

Sorry to sound alarmist but messing with "out of the socket AC current stuff" is best left to professionals.

5
  • 2
    Instead, get a quiter PSU.
    – pcapademic
    Jul 20, 2009 at 11:09
  • Backup + fire extinguisher? Jul 28, 2012 at 17:28
  • 1
    Given the nature of a PC PSU, this is excellent advice. The solution is to replace the PSU with a quieter one.
    – Stese
    Apr 3, 2019 at 15:48
  • 1
    If you know what you are doing you won't burn anything. If you made your house wiring and safety shutdown devices shield by your own hands - do not afraid to replace fan in PSU. Do not scare people.
    – puchu
    Apr 28, 2019 at 18:55
  • ""out of the socket AC current stuff" is best left to professionals." <- 1. No; and have a look at [DIY.SX](diy.stackexchange.com/). 2. The fan isn't powered by "out-of-the-socket-AC-stuff, it's DC-powered. 3. OP will not be replacing the fan while the PSU is plugged in naturally. Having said that - I'd be very careful about where the connection with the electrical tape is situated, since if it's misplaced within the PSU case then, yes, there could be some trouble.
    – einpoklum
    Dec 10, 2022 at 23:40
3

It's not problem replace PSU fan, but you void your warranty.

As for which fan to get: I prefer Noctua Fans.

2
  • I've got a spare AcoustiFan sitting around somewhere which should do the job.
    – GaryJL
    Jul 20, 2009 at 8:35
  • Please pay more attention to Noctua fans. There are fans for PSU - pressure optimized series or industrial. Other fans are not for PSU.
    – puchu
    Apr 28, 2019 at 18:57
2

What you suggest can definitely be done. I have replaced the fan in a PSU before, but it had a standard fan connector inside the PSU which made it easier.

I question your desire to plug the fan into the motherboard. While this would work, why not just splice the fan into the old fan wires? This would cause the two systems to be more independent of each other, create less of a wire mess, etc. Plus, with many PSUs the fan speed is controlled by the amount of heat or the current draw. You lose this functionality if you draw power from the motherboard.

3
  • There is a socket on the motherboard labelled PWR_FAN...
    – GaryJL
    Aug 14, 2009 at 8:04
  • And for RPM monitoring.
    – GaryJL
    Aug 14, 2009 at 8:08
  • Please do not use fan headers. Soldering fan is more reliable.
    – puchu
    Apr 28, 2019 at 19:05
1

Can it be done? Yes.

  • Many people (including myself) have simply cut the wires to the old fan and used some electrical tape to connect the wires to a new one. Works like a charm.
  • Its not rocket science.

Should it be done? No!

  • As some people have already said, the capacitors hold some charge even when the machine is switched off, which could discharge and deliver quite a significant electrical shock.
  • I don't know about other countries, but over here (Australia) only certified electricians are supposed to work on cables that are made to carry a 250v current (Technically we are not allowed to change light bulbs). Tinkering with the inside of a PSU is no exception to this. We can do other stuff with our computers because the cables coming out of the PSU are only 12v or something like that.
6
  • Why not? Please elaborate. ;)
    – Nikhil
    Aug 14, 2009 at 15:21
  • Elaborated a bit :) Aug 17, 2009 at 23:51
  • You can't even wire a plug? :O
    – Kurru
    Oct 10, 2011 at 3:34
  • Depends who you ask. The "right" thing to do is apparently get an an electrician to do it. Like if a business if trying to set a good example to their employees they will hire an electrician to wire a plug or change the light bulbs, but a lot of people also realise how stupid that is and just do it themself. Oct 10, 2011 at 3:55
  • Oh thats really stupid. In the UK I mounted 6 240v switches in a PSU case and made an elaborate switch panel for my external harddrives. Worked very well with no fire or anything ;) Dont use it anymore since getting a file server in anycase
    – Kurru
    Oct 12, 2011 at 4:32
1

Some expensive PSU (like Seasonics platinum) requires fan (Hong Hua fan) replacement. It is not only a problem for cheap PSU. Lets describe how to replace Hong Hua HA13525H12F-Z with proper fan.

You should select fan carefully:

  1. Find your stock fan product number (like HA13525H12F-Z).
  2. Find characteristic curve for this fan.
  3. Characteristic curve for Hong Hua is not available. You should select another PSU with same characteristics and same amount of heat (old Seasonic platinum platform with Sanyo Denki 9S1212H403 fans).
  4. Open Sanyo Denki 9S1212H401 (9S1212H403 has same characteristics) characteristic curve.

Sanyo Denki 9S1212H401

  1. Now you should select fan with characteristic curve above or equals to Sanyo (12v) curve. My solution is Noctua NF-A14 industrialPPC-2000.
  2. Ask Noctua to send you a characteristic curve for selected fan.

Noctua NF-A14 industrialPPC-2000

You can see that curves are about the same, difference is low.

  1. Buy your fan. Use any buck boost step down converter like LM2596 to test your fan. Starting voltage should be low <= 5.0v. My Noctua industrial fan has about 4.85v starting voltage, it is fine.
  2. Shutdown your computer, remove PSU from computer case and wait for 10 minutes. All your capacitors will be discharged during this time.
  3. Open PSU, remove Hong Hua, drill additional holes, solder Noctua directly to PSU mobo. It is better not to use fan pin headers, because Noctua motor starting current is high. Soldering is more reliable.
  4. Test how your fan controller is working using auto transformer on 100-250v with different load. You can use regular bulbs as a load.
  5. You can attach additional temperature sensors on radiators during tests. Sensors under load can be under high voltage. Just do not touch them and everything will be fine.
  6. Remove sensors and install PSU back to the computer case. Enjoy.

Results:

  • Hong Hua HA13525H12F-Z - 51.7 dbA
  • Noctua NF-A14 industrialPPC-2000 - 31.5 dbA

I think it is a safe solution for Seasonic platinum/titanium <= 850w/1000w. But of course it is your own risk, nobody is in charge.

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