My PC is making an annoying whine which I have self-diagnosed as coil whine because it seems to be coming from the power supply. This picture shows the rear of my PC, with some annotations.


I have found that if I hold a pack of post-it notes (or something of equivalent thickness) over the top vent marked with red, the noise cannot be heard. I am concerned though that doing so will possibly cause overheating; at least from what I've read elsewhere it could do.

My question is, given the presence of the "secondary" vent marked in blue, would this supply adequate air flow that the PSU fan could use to keep the PSU cool?

(I don't know enough about modern hardware components and - specifically - air flows, so am hoping that someone here does and can provide a reasoned answer)

Follow up question after answer accepted here: Safe method of blocking whining noise from PSU exhaust?

  • 1
    And this is a good idea? One takes heat from power supply and moves it. The other takes heat from motherboard and moves it. The have separate functions. Block off power supply and you will have problems. Aug 20, 2021 at 18:02
  • 1
    Considering the level of the question. It might be possible that it isn't even coil whine after all. It might be the fan inside the PSU or rather the air flow generated by said fan, which causes the noise. Regardless, do not cover up the vents.
    – sbecker
    Aug 21, 2021 at 18:54

2 Answers 2


No. Do not do this.

Power supplies typically push their exhaust out the back of the PC from that particular vent.

The other vent is, depending on the case fan setup, either an air input for the CPU fan or an exhaust for the CPU fan.

The vent you are proposing blocking is the PSU exhaust. Air is drawn into the case by the other fans, and a fan in the PSU itself pushes all that out the back of the PC there. By blocking it you will be preventing the PSU components from shedding heat. This may cause your PSU to overheat and/or die a lot sooner than it otherwise would.


No this is a bad idea. If the electronics are making a bad noise,
the safe answer is to replace the PSU before it fails outright.

Otherwise this might be better on https://electronics.stackexchange.com/ as a question about board-level repair and component replacement. Depending on your location, such a repair might require a qualified electrician. It all comes down to cost.

  • 6
    Coil whine isn't necessarily a sign of impending failure. Most of the time, it's just a sign that the manufacturer didn't include damping materials in all the right places.
    – Mark
    Aug 21, 2021 at 0:28
  • @Mark fair enough - we agree it is a board-level problem.
    – Criggie
    Aug 21, 2021 at 0:30
  • @Mark Good point. If this is the case, there is something to be said of the fact that a relatively "cheap" (not bad, just very cost effective..) is willing to forego the dampers, but not willing to leave out the vent. Even if it is created with a sheet metal stamp, there would be extra maintenance costs associated. As we all know, in a business, every penny matters. Someone would have had to approve that vent with those costs in mind. They obviously thought it was enough a necessity to justify it.
    – Nate T
    Aug 21, 2021 at 3:14

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