AIO resonant "hum"

jonessa · 29 Oct 2023 at 09:48

Hi folks,

I purchased a MSI Magcore C360 AIO for my 13700k build. It has the most annoying intermittent hum - it's completely unpredictable and doesn't change under load or temp, it's simply sometimes there and sometimes not.

Do all AIO coolers have this issue? I'm temped to swap for either an AIO where the pump is on the cooling block (this one is in the radiator), or just go back to air cooling. Loud fans don't bother me, but this hum is driving me insane. I can hear it over my headset!

Any advice greatly appreciated.

LuckyBenski · 29 Oct 2023 at 09:58

Have you poked around the case for any loose or resonant components? Could be unrelated or it could be the pump is vibrating something that makes the noise.

I'd first try to track it down by setting the pump to different speeds, then same with fans. For me the most annoying hum came from hard drives and that took a while to pinpoint!

Mcnumpty2323 · 29 Oct 2023 at 10:40

Hum from the pump?
Or possible resonance/vibration from the case/something in the case?
When I used swiftech AIO
Those had the pump in the radiator
Some pc cases it caused vibration/resonance
Of the panel it was mounted to
I used to shove rubber washers between the rad and case

As luckybenski said
Alter pump speed see if has any effect
If possible set fans to zero rpm
Or disconnect them temporarily
To make it easier to locate where the noise
Is coming from

jonessa · 29 Oct 2023 at 18:45

LuckyBenski said:
Have you poked around the case for any loose or resonant components? Could be unrelated or it could be the pump is vibrating something that makes the noise.

I'd first try to track it down by setting the pump to different speeds, then same with fans. For me the most annoying hum came from hard drives and that took a while to pinpoint!

i've poked and prodded but haven't found anything loose.... also - I can't seem to control the pump speed from the BIOS. It's registering it at 4300rpm, but my only control options are PWM or DC?

I'm going to take the cooler and put it outside of the case to see if that fixes the issue, and then.....

Mcnumpty2323 said:
Hum from the pump?
Or possible resonance/vibration from the case/something in the case?
When I used swiftech AIO
Those had the pump in the radiator
Some pc cases it caused vibration/resonance
Of the panel it was mounted to
I used to shove rubber washers between the rad and case

As luckybenski said
Alter pump speed see if has any effect
If possible set fans to zero rpm
Or disconnect them temporarily
To make it easier to locate where the noise
Is coming from

....try some rubber washers as suggested if the sound goes away when it's running outside of the case.

I just can't fathom why it's so intermittent though? the pump speed is pretty much constant, so i'm guessing it's air at certain points?

LuckyBenski · 29 Oct 2023 at 20:36

jonessa said:
i've poked and prodded but haven't found anything loose.... also - I can't seem to control the pump speed from the BIOS. It's registering it at 4300rpm, but my only control options are PWM or DC?

If it's a 4 wire plug on the pump it is PWM controllable. If not, you could try DC control but YMMV with pumps.

I'd suspect the pump speed is fixed if it has a 3 pin plug/3 wires. However if it has a USB connection or similar then it's possible it regulates its own speed.

jonessa · 30 Oct 2023 at 00:22

LuckyBenski said:
If it's a 4 wire plug on the pump it is PWM controllable. If not, you could try DC control but YMMV with pumps.

I'd suspect the pump speed is fixed if it has a 3 pin plug/3 wires. However if it has a USB connection or similar then it's possible it regulates its own speed.

Yea - 3 pin plug...

anyway - found the problem. The fan directly below the pump, coupled with smart fan mode was the issue. The curve saw the fan speed increase between 35 and 45 degrees. This, as it turns out, was defaulted to a RPM range causing the horrific resonance. I've backed the fan off and created a bigger step in the RPM change. Gaming perfectly at 45 degrees now with no noise, and when stress-testing, I've set the fans on the Cooler to bypass the RPM range causing the issue! The intermittent nature was caused by the temp hovering between 35 and 45 degree's causing this fan to spin up at random points just above the idle temp.

Thanks to all that commented with suggestions!