[SOLVED] AIO CFM measures total of all fans or per fan?

[Kevinstarcade]

I've been wanting to replace my CPU's stock cooler and I've got my eyes on Cooler Master's MasterLiquid ML240R. In the specifications, it says the max CFM is 66.7. I've also looked at the fans they use (which are the MasterFan MF120R) and they say their max CFM is 59. I'm wondering if the CFM rating for the AIO takes the total CFM of both fans and it drops significantly due to air resistance or have they modified their fans and each gives a 66.7 CFM? The mmH2O also changes from 2.14 on the fans to 2.34 on the AIO.

P.S. is 2.14/2.34 mmH2O a high enough pressure? I'm new to AIO cooling

Edit: Links here
AIO: https://www.coolermaster.com/catalo...olers/masterliquid-ml240r-rgb/#Specifications
Fans:https://www.coolermaster.com/catalog/coolers/case-fan/masterfan-mf120r-argb/#Specifications

 

[Karadjgne]

Cfm by itself is useless info. It needs to be balanced against static pressure, fin density, fin depth, rpm etc. Afaik the cfm they refer to is what's moved on the back side of the rad, regardless of what's actually output from the fans, at rated maximum rpm of the fans.

Which if the aio is balanced against the load, should never happen except in performance mode during a stress test.

The ML240R is the best of the ML240 series, and a respectable aio in its own right, usually placing in the top 5.

Ranking by cfm won't get you a better AIO, or better fans, the Noctua NF-F12 has lower cfm than many other radiator rated fans, yet is arguably the best radiator fan produced so far.

 

[Kevinstarcade]

Cfm by itself is useless info. It needs to be balanced against static pressure, fin density, fin depth, rpm etc. Afaik the cfm they refer to is what's moved on the back side of the rad, regardless of what's actually output from the fans, at rated maximum rpm of the fans.

Which if the aio is balanced against the load, should never happen except in performance mode during a stress test.

The ML240R is the best of the ML240 series, and a respectable aio in its own right, usually placing in the top 5.

Ranking by cfm won't get you a better AIO, or better fans, the Noctua NF-F12 has lower cfm than many other radiator rated fans, yet is arguably the best radiator fan produced so far.

I'm not ranking the AIOs based on their CFM. I'm trying to balance the air pressure inside my case and I was wondering the CFM.

 

[Karadjgne]

Heh. That's impossible. Fans don't always, in fact almost never run at full rated speeds. They'll generally run 30-70% going from idle to gaming loads.

A fan curve is just that, a curve where you'll generally see around 95% of actual performance in the first 70% of the duty cycle, the last 5% in the last 30% of duty cycle. Meaning with a 2000rpm fan, you'll get almost all the cfm/sp by the time you reach @ 1500rpm, everything from 1501-2000rpm being nothing but noise with little gain.

Fans on different headers are speed dictated by different temp areas as the sensors are located in different places on the motherboard. So exhausts might be at 1500rpm, intakes at 1000rpm, ans even with identical fans, that's going to create a difference. Changing fans is even worse, different designed blades have different properties, so respond differently, even responding differently with a move from 120mm to 140mm.

Basically, with the sheer amount of variables that goes into airflow characteristics, it's impossible to get a balanced flow, that starts out balanced, stays balanced. You're going to have a decent range of movement in pressure gradients no matter if what goes in equals what goes out on paper.