Radiator fan speed diminishing returns at what speed?

[lancerzero9]

When liquid cooling in a pull configuration, after what fan speed do you not see much gains for the increased noise level? Some have told me anything above 50% (depending on the fan max rpm) makes very little cooling difference and you just get a lot more noise with smaller cooling ability. Some have said 65% and some 75%. But nobody has ever told me anything above 80% is worth the noise.

I thought I would come here and get a few more opinions as I have a not so quiet case and want to lower the fan speed as mush as possible. Thanks for any info.

 

[JackNaylorPE]

There's no universal answer Obviously the question is very different depending upon whether you are talking about a 3,000 rpm fan or a 1200 rpm fan. With today's radiators, the ideal fan speed for an adequately sized set of rads is 1200 rpm .... these will remain silent up to about 850 rpm.

In small cases where ya can't fit the radiator(s) you need, if not sensitive to noise, you can go up to 1800 rpm. With CLCs that typically use 2700 rpm, they are going to be noisy throughout most of the operational range. Swap out the 2700 rpm Corsair fans on the H100i for say $30 Noctua AF-15s at 1500 rpm and you lose about 40% of the H100i's thermal performance.

It's not the % of speed that affects performance / noise but the actual rpm.

For the cold hard numbers, look at martinsliquidlab
https://martinsliquidlab.wordpress.com/2012/04/15/alphacool-nexxxos-xt45-360-radiator/4/

 

[lancerzero9]

Thanks for the help. I never knew of the site you recommended. I should have stated that I'm using the CM Nepton 240mm with 2 Corsair sp120s PWM fans.

It seems that by the data I have read here that 1400 rpms with my setup seems to be the highest I should go below 80c given how loud my fans get above such an rpm. When my temps hit higher than that I will just put on the headphones deal with the higher rpms.

 

[JackNaylorPE]

Pull works better up to about 1500 rpm .... 1750 and above pull works better.... in the middle, it's the same.