Pump PWM %/speed ?

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kyriptic

Limp Gawd
Joined
Dec 30, 2012
Messages
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Just finished my first water cooling build and getting around 30c with very low pwm on the pump. Just wondering what people usually run their pump at and if there is any reason to no run the pump super low if your temps are looking good?
 
What I've read is that basically, you want to set the pump as high as you're willing to tolerate in regards to noise. They're adjustable so you can tailor them to your needs in terms of loop restrictiveness, size and complexity.
 
Exactly what VanGoghComplex said...set the pump speed to 100%, then back it down a 10% at a time until you don't notice or can't hear it. Unless temps are a big issue, then you may need to bump it back up.
 
Did you guys read what he said? He's using a PWM pump. They're designed to run at a range of speeds automatically.

You guys sound like you're referring to the D5 Vario pumps, that were controlled via DC and had a smaller adjustable range.



If what you're saying is still true then so be it, but I don't see why Laing would be making PWM D5 pumps if they weren't designed to take advantage of the single most desirable thing about PWM control - the ability to set fan curves based on temp.
 
GlacierNine said:
Did you guys read what he said? He's using a PWM pump. They're designed to run at a range of speeds automatically.

You guys sound like you're referring to the D5 Vario pumps, that were controlled via DC and had a smaller adjustable range.



If what you're saying is still true then so be it, but I don't see why Laing would be making PWM D5 pumps if they weren't designed to take advantage of the single most desirable thing about PWM control - the ability to set fan curves based on temp.
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Thermally, it's difficult to set pump curves appropriately for both fans and pumps. Setting a single fan curve based on temps is easy. Setting two curves based on temp where they have complex interactions is far more challenging. Not to mention, when you're dealing with a custom loop, pump speed does NOT scale well with temps. Once you get above a certain minimum flow rate, adding more pump speed has almost zero impact on your temps. And that minimum flow rate is actually pretty damn low in most loops.

This is why most builders, even those that run PWM pumps, will set them and forget them. The PWM has the advantage over the older manual vario's in that I don't have to crack open the case and possibly remove the pump cover to get to the adjustment screw.

Second reason - noise. Pumps are arguably one of the louder components, and if the speed is ramping up and down all the time with temp, it's far more noticeable for the user.
 
Bandalo said:
Thermally, it's difficult to set pump curves appropriately for both fans and pumps. Setting a single fan curve based on temps is easy. Setting two curves based on temp where they have complex interactions is far more challenging. Not to mention, when you're dealing with a custom loop, pump speed does NOT scale well with temps. Once you get above a certain minimum flow rate, adding more pump speed has almost zero impact on your temps. And that minimum flow rate is actually pretty damn low in most loops.

This is why most builders, even those that run PWM pumps, will set them and forget them. The PWM has the advantage over the older manual vario's in that I don't have to crack open the case and possibly remove the pump cover to get to the adjustment screw.

Second reason - noise. Pumps are arguably one of the louder components, and if the speed is ramping up and down all the time with temp, it's far more noticeable for the user.
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What he said.

PWM on pumps is a convenience feature as opposed to a manual setting on the pump or cable. Controlling pump speed on temperature yields insignificant benefits and is very tricky.
 
So there is no issues with running the pump at like 50% or lower pwm if you're happy with the temps? just from feeling the tubing i can still feel a tiny bit of the flow... was just worried if I set it to low it might hurt the pump or not be strong enough to push the water?
 
kyriptic said:
So there is no issues with running the pump at like 50% or lower pwm if you're happy with the temps? just from feeling the tubing i can still feel a tiny bit of the flow... was just worried if I set it to low it might hurt the pump or not be strong enough to push the water?
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It should move water at the minimum settings. I'd advise not going below 30%, just to ensure the pump starts every time, but that's just my personal paranoia. You won't damage the pump at any PWM setting.
 
kyriptic said:
So there is no issues with running the pump at like 50% or lower pwm if you're happy with the temps? just from feeling the tubing i can still feel a tiny bit of the flow... was just worried if I set it to low it might hurt the pump or not be strong enough to push the water?
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No problem at all. Turning pumps slower won't hurt them.

As long as you're meeting a certain minimum flow rate, which will be defined by the specific characteristics of your loop, your performance will be practically unchanged. As a hypothetical example, a loop will perform just the same between 20% and 100%, but below 20%, cooling performance will drop off noticeably. Those are fictional numbers, but the principle is the same.
 
Thanks for the help guys that makes sense. I'm still going to make a pwm curve for fans + pump, but its more to manage noise at low temps. Once temps go up I'm planning on cranking up the fans first then if temps still rise crank up the pump and fans more. Most just want to make it as quiet as possible during idle + low load then make more noise at high load so temps don't rise past a point.
 
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