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Knocking sound from psu

poland400
By poland400
in Troubleshooting
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Go to solution Solved by mariushm,

I can't play the video, doesn't work for some reason. 

 

Just don't touch anything but the case and maybe the fan. Unplug it from mains and the psu SHOULD discharge within around 10-20 seconds. There's circuitry inside that takes care of discharging those high voltage capacitors, but very rarely, shit happens and that circuitry may fail to work, and then you could get zapped (or you could die in extreme cases)
 

So try not touching the heatsinks inside as those may still hold charge. The fan and the exterior of the case is safe. 

 

Most power supplies will have a plastic bit between the metal case of the psu and the fan, blocking a small section of the fan. That is to guide the air flow from the fan to blow more towards the area of the power supply that get hotter. 

Sometimes that plastic foil bends or breaks or stuff happens that it may touch the plastic blades of the fan and then you may hear the plastic blades hitting that plastic foil and you get that noise. If you put it on one side, the gravity or the air being sucked into the psu will probably not cause that plastic to hit the blades so you don't have that noise anymore. 

 

So you could try unscrewing the fan to remove that foil, put back the fan and see if you still get the noise. 

 

If that's not the issue, it's possible the fan is failing, if it's ball bearing one of the balls may be chipped or deformed and you get that noise. If it's some other kind of fan, it could be it's worn out due to bad lubrication or some other reasons. 

 

A simple solution would then be to just swap the fan with another, but you have to pay attention to the fan's technical specifications (how much rpm, how much air flow (CFM/m3 or some other value), how much pressure... a regular case fan may not push enough air into the power supply through that grid on the metal case. 

 

 

Posted
45 minutes ago, poland400 said:

I have a corsair cx power supply which has a Knocking noise for a while but it's driving me mad now any help how to DIY fix this or just buy a new psu?  The psu is around 10 years old

 

You sure its PSU? Sounds like a fan hitting a cable or a dead bearing on a fan.

Gaming PC:

CPU: Ryzen 5800X3D | Motherboard: Gigabyte B550 Elite V2 | RAM: Crucial 2x16gb, 3200  JEDEC. | PSU: EVGA SuperNova 750 G3 | Monitor: LG 27GL850-B , Samsung C27HG70 | 
GPU: Asus Prime RTX 5070ti OC| Sound: Odac + Fiio E09K | Case: Fractal Design R6 TG Blackout |Storage: Kingston Renegade 2TB and Corsair MP510 960gb | Cooling: CPU: Alphacool ST30 420mm rad, Alphacool CPU and GPU Core LT and Core blocks, D5 pump and res combo 

 

Linux PC:

CPU: Ryzen 7700| Motherboard: Asus A620M-CSM | RAM: Crucial Pro 2x48gb, 5600  JEDEC. | PSU: Corsair CX750 | Monitor: LG 27GL850-B , Samsung C27HG70 | 
GPU: MSI Gaming X RTX 3090 | Case: Lian Li Dan Cases A3-mATX black |Storage: SN7100 2TB + Samsung 860 EVO 512gb | Cooling: CPU: Thermalright Peerless Assassin Mini Fan(s): Noctua 1x NF-A14x25 Chromax

 

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12 minutes ago, DoctorNick said:

You sure its PSU? Sounds like a fan hitting a cable or a dead bearing on a fan.

Yes it's coming from the psu, i took the pc apart to find the noise and it's coming from the psu, I fixed it at one point by putting the psu on the side but now it doesn't make a difference how I put it

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4 minutes ago, poland400 said:

Yes it's coming from the psu, i took the pc apart to find the noise and it's coming from the psu, I fixed it at one point by putting the psu on the side but now it doesn't make a difference how I put it

You can try taking off the PSU cover. Be careful though. Let it sit some time before opening it, to let the caps decharge. Check if the fan cable is touching the blades. If not, swap the fan.

Gaming PC:

CPU: Ryzen 5800X3D | Motherboard: Gigabyte B550 Elite V2 | RAM: Crucial 2x16gb, 3200  JEDEC. | PSU: EVGA SuperNova 750 G3 | Monitor: LG 27GL850-B , Samsung C27HG70 | 
GPU: Asus Prime RTX 5070ti OC| Sound: Odac + Fiio E09K | Case: Fractal Design R6 TG Blackout |Storage: Kingston Renegade 2TB and Corsair MP510 960gb | Cooling: CPU: Alphacool ST30 420mm rad, Alphacool CPU and GPU Core LT and Core blocks, D5 pump and res combo 

 

Linux PC:

CPU: Ryzen 7700| Motherboard: Asus A620M-CSM | RAM: Crucial Pro 2x48gb, 5600  JEDEC. | PSU: Corsair CX750 | Monitor: LG 27GL850-B , Samsung C27HG70 | 
GPU: MSI Gaming X RTX 3090 | Case: Lian Li Dan Cases A3-mATX black |Storage: SN7100 2TB + Samsung 860 EVO 512gb | Cooling: CPU: Thermalright Peerless Assassin Mini Fan(s): Noctua 1x NF-A14x25 Chromax

 

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22 minutes ago, DoctorNick said:

You can try taking off the PSU cover. Be careful though. Let it sit some time before opening it, to let the caps decharge. Check if the fan cable is touching the blades. If not, swap the fan.

i get it a psu cap can kill you but why oh why don't these companies put warning labels on them? simple negligence?  

 

i don't think a "do not open" label with no explanation whatsoever does really cut it... 

The direction tells you... the direction. 

-Scott Manley, 2021

 

 

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I can't play the video, doesn't work for some reason. 

 

Just don't touch anything but the case and maybe the fan. Unplug it from mains and the psu SHOULD discharge within around 10-20 seconds. There's circuitry inside that takes care of discharging those high voltage capacitors, but very rarely, shit happens and that circuitry may fail to work, and then you could get zapped (or you could die in extreme cases)
 

So try not touching the heatsinks inside as those may still hold charge. The fan and the exterior of the case is safe. 

 

Most power supplies will have a plastic bit between the metal case of the psu and the fan, blocking a small section of the fan. That is to guide the air flow from the fan to blow more towards the area of the power supply that get hotter. 

Sometimes that plastic foil bends or breaks or stuff happens that it may touch the plastic blades of the fan and then you may hear the plastic blades hitting that plastic foil and you get that noise. If you put it on one side, the gravity or the air being sucked into the psu will probably not cause that plastic to hit the blades so you don't have that noise anymore. 

 

So you could try unscrewing the fan to remove that foil, put back the fan and see if you still get the noise. 

 

If that's not the issue, it's possible the fan is failing, if it's ball bearing one of the balls may be chipped or deformed and you get that noise. If it's some other kind of fan, it could be it's worn out due to bad lubrication or some other reasons. 

 

A simple solution would then be to just swap the fan with another, but you have to pay attention to the fan's technical specifications (how much rpm, how much air flow (CFM/m3 or some other value), how much pressure... a regular case fan may not push enough air into the power supply through that grid on the metal case. 

 

 

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