Lowest RPM I should go for 140mm fan? (Specifically NF-A15 and Fractal Dynamic GP-14)

[crystal6tak]

Will be doing a build with NH-D15 + Define R5 soon (might make a build log who knows)

 

And I'm all about silence (Got a Asus Strix GPU and Corsair RM series PSU just for their fan off ability)

 

I'll likely be controlling the NF-A15 fan with SpeedFan and try and see if I'm lucky enough to control the Dynamic GP14 fans (dang it 3 pins).

 

Now obviously turning them completely off is probably a bad idea, need some airflow at least, so I'd like to know if anyone tested 140mm fans to see just how low of an RPM they should go before it's not worth it anymore to lower it any further as airflow will go way down?

 

Specifically the NF-A15 and the Dynamic GP14 fans, how low of an RPM should I go before turning them any lower won't be worth the extra silence cause airflow would decrease too much? Or does airflow and RPM follow a linear curve?

 

All replies are appreciated thank you!

[Enderman]

airflow and pressure vs rpm is pretty linear

not exactly, but you can assume it is in this case

[norgeek]

I recently built a Z170Deluxe/6700K in a Define S. I'm using an NH-D15, and for all but intensive work the only fans in the system that aren't shut down completely are the two noctuas - one on the cooler and one as exhaust - running at 300rpm. I can't hear them at all, the high-end fridge across the room makes more sound. System normally operates at 34 degrees Celsius, somewhere below 100 Fahrenheit.

I have 3 GP-14's up front that kick in once it gets hot (rarely). At the lowest RPM, which is considerably higher than the Noctuas, they're quite audible (compared to an otherwise virtually noiseless system). But effective!

As it's my moms facebook machine I don't have a discrete GPU in it yet. I'll probably throw a 970 in there at some point so I'm not limited to Steam streaming for my kitchen gaming sessions. Depending on how loud the GPU is I might consider Noctuas in the front as well.. but even with the GP-14's you should end up with a pretty quiet system even under load. Assuming you're able to control them.

Keep in mind that the windowless cases are coated with noisedampening foam on both sides, whereas the windowed case is (obviously) not. It's a style vs. noise compromise, luckily it was easy for me to choose silence.

[crystal6tak]

I recently built a Z170Deluxe/6700K in a Define S. I'm using an NH-D15, and for all but intensive work the only fans in the system that aren't shut down completely are the two noctuas - one on the cooler and one as exhaust - running at 300rpm. I can't hear them at all, the high-end fridge across the room makes more sound. System normally operates at 34 degrees Celsius, somewhere below 100 Fahrenheit.

I have 3 GP-14's up front that kick in once it gets hot (rarely). At the lowest RPM, which is considerably higher than the Noctuas, they're quite audible (compared to an otherwise virtually noiseless system). But effective!

As it's my moms facebook machine I don't have a discrete GPU in it yet. I'll probably throw a 970 in there at some point so I'm not limited to Steam streaming for my kitchen gaming sessions. Depending on how loud the GPU is I might consider Noctuas in the front as well.. but even with the GP-14's you should end up with a pretty quiet system even under load. Assuming you're able to control them.

Keep in mind that the windowless cases are coated with noisedampening foam on both sides, whereas the windowed case is (obviously) not. It's a style vs. noise compromise, luckily it was easy for me to choose silence.

Interesting... Wait one thing I don't get. "3 GP-14's up fron that kick in once it gets hot". So you do have it controlled in some way? How are you controlling it?

 

And also yea, I got the non windowed version of R5. Wouldn't want the window anyways as my internal is going to have 7 different colors 

[norgeek]

The fans are all controlled by the motherboard, using Asus Fan Xpert 3. It's really easy to set up profiles for all the fans, both 3pin and 4pin. How much control you get depends on the motherboard and manufacturer software, the MSI board I have in my file server is a lot less helpful in comparison.

[WoodenMarker]

I run my NF-A15's at 7% since that's about as low as I've been able to run them. They ramp up to ~20% when at load but that's not often. 

Just set the fan speed ramp up to keep your temps low enough. This may take some testing but such is with cooling and determining temps. 

[crystal6tak]

I run my NF-A15's at 7% since that's about as low as I've been able to run them. They ramp up to ~20% when at load but that's not often. 

Just set the fan speed ramp up to keep your temps low enough. This may take some testing but such is with cooling and determining temps. 

I see... How are you controlling your fan speed btw? I see ppl recommend speedfan while some ppl say speedfan will mess up your rig. So not sure what's going on, never tried speedfan before.

[WoodenMarker]

I see... How are you controlling your fan speed btw? I see ppl recommend speedfan while some ppl say speedfan will mess up your rig. So not sure what's going on, never tried speedfan before.

I control the fans through my motherboard's software although I used to use SpeedFan. I've never seen anyone mess up their system with SpeedFan and the worse it would probably do is confuse the user. All of my fans are running off of a fan splitter to my cpu_fan header.