CPU Pump Humming Noise

[sidewinder1911]

Alright, so I just now put together a new system and was running it for a while with the side panel off in case I encountered any problems. After about 2 hours, the CPU pump on my AIO liquid cooler started making a very audible humming noise. The pump is plugged into my CPUFAN header, and although the header is 4-pin PWM, the pump's plug is only 3-pin, and I double checked in the BIOS to make sure that the pump was running at a constant speed, and it was (around 2500rpm).
Here is a link to the recording I made with my phone. Note that the audio level in the video may be a lot louder than it actually is. https://drive.google.com/file/d/0B8tGEvqjzkSoeFhoRDFzZ0tKeU0/view?usp=sharing

 

[Karadjgne]

Some pumps do get a hum. It's unavoidable. You have a moving diaphragm inside the pump head that's vibrating back and forth to move the fluid.

On the other side of the coin, some pumps have a slight issue with some motherboards. The motherboards themselves are thinner than standard, barely, but this means when you tighten the nts/screws down, they stop short of 'tight'. The remedy for this is some cheap nylon/teflon washers (thin ones- maybe 2mm thick) and you slide them in between the backplate and the motherboard. This has the affect of shortening the screws so the nuts don't hit the bottom fully on the bracket. Pumps work better when nice and tight to the cpu, tighter than most aircoolers need. Should help dampen pump vibrations.

Your cpu_fan header is pwm. 12v, ground, tach and pwm signal wires. By using a 3 pin on the header, Corsair makes it so the pump only sees 12v,ground and tach. This absolves them of user error damage due to 3 pin headers not running the full 12v full speed. You can put the pump anywhere you like, as long as it's running 100%,either by bios or software. Cpu_aux is a good header for this if you have one, them control the rad fan through the cpu_fan header as is normal. This'll mean your rad fan idles when the pc idles, cuts down on a lot of noise, but the pump still runs at full speed.

 

[sidewinder1911]

Some pumps do get a hum. It's unavoidable. You have a moving diaphragm inside the pump head that's vibrating back and forth to move the fluid.

On the other side of the coin, some pumps have a slight issue with some motherboards. The motherboards themselves are thinner than standard, barely, but this means when you tighten the nts/screws down, they stop short of 'tight'. The remedy for this is some cheap nylon/teflon washers (thin ones- maybe 2mm thick) and you slide them in between the backplate and the motherboard. This has the affect of shortening the screws so the nuts don't hit the bottom fully on the bracket. Pumps work better when nice and tight to the cpu, tighter than most aircoolers need. Should help dampen pump vibrations.

Your cpu_fan header is pwm. 12v, ground, tach and pwm signal wires. By using a 3 pin on the header, Corsair makes it so the pump only sees 12v,ground and tach. This absolves them of user error damage due to 3 pin headers not running the full 12v full speed. You can put the pump anywhere you like, as long as it's running 100%,either by bios or software. Cpu_aux is a good header for this if you have one, them control the rad fan through the cpu_fan header as is normal. This'll mean your rad fan idles when the pc idles, cuts down on a lot of noise, but the pump still runs at full speed.

Don't have a CPU AUX header unfortunately. My cooler is a Fractal Design T12, but that shouldn't really change anything right? By the way, I should mention that according to Afterburner and CAM my i5-6500 at idle is hovering at 36-40 degrees, does that sound reasonable?

 

[Karadjgne]

Those are reasonable temps, but much depends on ambient temps, if it's hot by the pc, temps will be higher, if the pc is in a room with ac in the low - mid 70°F then they are a little high. Also depends on the fan curve. If you have the cpu fan curve set to silent, it'll spin slower, and not speed up as fast, so temps are a little higher, but a lot quieter. The pump head should be nice and tight to the cpu. Also, in CAM, are you seeing cpu temp or liquid temp, they'll be different.

 

[sidewinder1911]

Those are reasonable temps, but much depends on ambient temps, if it's hot by the pc, temps will be higher, if the pc is in a room with ac in the low - mid 70°F then they are a little high. Also depends on the fan curve. If you have the cpu fan curve set to silent, it'll spin slower, and not speed up as fast, so temps are a little higher, but a lot quieter. The pump head should be nice and tight to the cpu. Also, in CAM, are you seeing cpu temp or liquid temp, they'll be different.

I see what you mean. Pump head as far as I know is as tight as possible, though I believe when I installed it outside the case the pump head was VERY slightly tilted, barely noticeable though. I'm not sure which one CAM is showing me, underneath CPU it simply says temp, and then the current temp.

 

[Karadjgne]

That'll be cpu temp then.

Thetes a slight difference in the retaining frame being tight to the screws and the pump itself being tight on the cpu. This is why the nylon washers are suggested, to shorten screw length at the stop and allow for a few more thread turns, further pressuring the frame down, which puts added pressure on the pump-cpu. A 1/2 turn difference can make a 5°C difference, just make sure the pump is tightened down in an 'X' pattern, not a circular pattern. Get all the screws on, lightly finger tight, then X 1/4-1/2 turn each screw in succession, constantly moving. Tightening 1 screw at a time in a circular pattern can and will warp the retaining frame and creates a difference in pressure from 1st to last screw, which can allow for vibrations in the pump head, or a humming noise.