Silence

[cisto1999]

I am planning to build a watercooled rig.

What is planned: a 9x140mm Radiator an two 240s to cool a CPU (2600k) and probably a gtx 580. I know that´s an overkill. But my plan is that the radiators work most of the time passive but i also want to have the ability to overclock and cool the system actively.

 

My question: I am thinking of getting the Swiftech MCP35X PWM for this system. I want to run it as quiet as possible. So what to you think: would two of these pumps will run more quiet together if each runs at about 25 % or will one be quieter running at about 40 %? The other positive element of running two pumps will be redundancy.

 

Thanks for your postings.

 

[IVIeLt]

Run 2 pumps at lower speeds. Similar concept to fans, if you run more of them at a lower speed you get the same airflow but less noise.

[Ghost]

My question: I am thinking of getting the Swiftech MCP35X PWM for this system. I want to run it as quiet as possible. So what to you think: would two of these pumps will run more quiet together if each runs at about 25 % or will one be quieter running at about 40 %? The other positive element of running two pumps will be redundancy.

Two pumps sometimes have noise problems because they emit the same sound so the sound effectively doubles. Its better to use two different pumps for silence.

 

Source: "Martins Liquid Lab"

[IVIeLt]

Two pumps sometimes have noise problems because they emit the same sound so the sound effectively doubles. Its better to use two different pumps for silence.

 

Source: "Martins Liquid Lab"

 

On that theory, If both pumps are running at a different speed would they then be quieter because they are emitting different sounds?

[Ghost]

On that theory, If both pumps are running at a different speed would they then be quieter because they are emitting different sounds?

Yes.

 

Although I am no expert in sound.

[alpenwasser]

On that theory, If both pumps are running at a different speed would they then be quieter because they are emitting different sounds?

The phenomenon that is at play here is a beat.

I last did some calculations in physics on those things in summer 2011, so I'm a bit hazy

on the details tbh.

If I recall correctly, the frequencies at play here need to be relatively close to each

other (but not identical), otherwise the phenomenon, while still present, will be perceived

differently (and can even be a desired effect in musical instruments). Once the difference

between the two frequencies goes above a certain limit, you will start to perceive them

as two separate tones, essentially (EDIT: Which is what you want in this case /EDIT).

Bottom line: You can still have this effect with two different pumps, but I don't think

that it will be very likely. If you wanted to make sure not to have this problem, put your

pumps on a controller (or buy something like the D5 vario, which you can adjust in its

speed). That way you can just tune the pumps manually if you should encounter such an

effect and set them both to speeds different enough that the effect does not occur.

EDIT 2: I've just read Martin's article in which he mentions this (link).

From his description it sounds exactly like this phenomenon.

[R4STABAN]

This is a ridiculous amount of radiators sir!

 

I used to run a 9x140 rad external with the phobya 4 x 200mm fan bracket. That allows you to run the 200mm fans so slowly that you an't hear them unless you put your ear next to them.

 

External is horrible though.. I modded my rv02 to take rads.

[tabuburn]

This is a ridiculous amount of radiators sir!

 

I used to run a 9x140 rad external with the phobya 4 x 200mm fan bracket. That allows you to run the 200mm fans so slowly that you an't hear them unless you put your ear next to them.

 

External is horrible though.. I modded my rv02 to take rads.

Well, unless he's using the Caselabs TX10 cases. Those can accommodate ridiculous amounts of rads.