Faint humming coming from computer, but from where?

[Tehuti]

For the past few days I have noticed a somewhat persistent very faint humming sound coming from my computer. It's not always present, it seems to fade in and out as though my GPU fans are starting up and then turning off, which is not the case.

It's not exactly loud, but it is detectable from sitting at my computer and it can be very annoying. When I get on my knees and put my ear to my case I can barely hear it or I can't hear it at all, making pinpoint this hum extremely difficult. It seems to be in the area of my CPU/Hyper 212 Heatsink, but again, it's rarely noticeable when I'm at the computer's level, more so when I'm sitting or standing near my computer.

I put my ear to the PSU and I couldn't hear anything, same with the case fans and HDD, which narrows it down to the GPU or CPU itself. I assume this is an extremely quiet coil whine of sorts.

I really wish I could figure this out. It's not coming from the speakers either, as I've unhooked them and put my ear to them.

So to sum it up. Faint, very quiet hum that fades in and out like a fan starting up and then quieting down. It's most noticeable when sitting at the computer, even while typing right now I can hear it fading in and out, but yet when I get on the floor I can't hear anything! It's definitely coming from the computer as it's not present when the computer is off. I'm tempted to turn my GPU fans up just to drown it out.

Specs:

Asus H81M-K
Intel i5 4690K @ Stock 3.5 GHz with Hyper 212 Heatsink
MSI GTX 970 4GB - Not Overclocked (Fans are not running when I hear this hum)
Ripjaws 8GB DDR3 1600
WD Blue 500GB
Rosewill Challenger Case

All temperatures are in the range of 30-45C when idle and no higher than 65 when under load.

 

[dudio]

You may want to try a monitoring software like HWInfo64 to monitor hardware useage and fan rpm's to see if you can correlate the sound to hardware or fan activity.

 

[Zerk2012]

Best way to find a sound in a PC is take the side panel off, use a empty roll of paper tows, one end up to your ear and move the other end around till you can find the noise.

 

[atljsf]

or is coil whine from the gpu or is the psu

if it is the gpu, not much can be done, if it is the psu, i would change it

but you need to be sure from where the noise is coming from, so you don't buy the wrong part

 

[Tehuti]

Doesn't appear to be the PSU as the noise is more around the middle/top of my case, but again super faint and always seems to vanish when I put my ear to case. When I'm sitting at PC typing it can get quite loud, oddly! I've been using HWMonitor to correlate fan RPM. I have a feeling it's the heatsink, but I can't be sure. I'm gonna try this paper roll method. Also, I tried to turn down my Hyper 212's fan in the BIOS and it seems to do nothing to the RPM. It's still within the range of 800-1050.

 

[atljsf]

if you apply pressure over the case, it is fans vibrating, be sure to screw them well, if you detect that one of them is vibrating too much after screwing the screws properly, change it

 

[Tehuti]

I think the easiest solution is replacing my heatsink's fan and the fans on my case. A few are giving out anyways. I managed to get my CPU fan below 700 RPM and the noise is still present and just as vague and faint as ever. At this point I'm convinced it's the GPU (perhaps a very, very faint coil whine) or SYSFANIN, which I assume are case fans. I thought it was the CPU fan but after watching it go from 700-1050 RPM without much change it seems less likely to be that fan. I also switched out my motherboard yesterday to a new one due to damaged pins and the noise has persisted with the new motherboard. I'm 100% sure it's not the PSU, so yeah, guess I should replace those case fans. If it's still present then it's probably the GPU so I'll just have to survive with it like it. Luckily in the evenings there's enough noise in my house where I don't notice it whatsoever. It's only in the early day that I notice it while doing work on the computer.

Thanks for comment.

 

[atljsf]

if you changed the mainboard, or is coil whine or fans

but remember to check the psu, i had psus in the past that made noises and finally died

 

[Zerk2012]

Do the empty roll of paper tows works every time.