Pressure-optimised or airflow-optimised fan for rear exhaust?

[kingmustard]

I currently have a be quiet! Shadow Wings 2 (120mm, 39 CFM, 450-1100 RPM, PWM) as the exhaust for my PC .

 

Whilst it's very quiet, it doesn't seem to be extracting a lot of heat out of the system. Presumably, this is due to it having a 39 CFM peak.

 

Therefore, I am trying to decide between the Noctua NF-F12 PWM and the Noctua NF-S12A PWM.

 

This Noctua page suggests:

 

"NF-F12 is a pressure-optimised fan that excels on heatsinks and radiators and the NF-S12A is an airflow-optimised fan that provides excellent results as a case fan and in other low- to mid-impedance applications."

 

Presumably, I'll want to go for the NF-S12A then, but I thought I'd check with you all first.

 

Full system details.

[WereCatf]

2 minutes ago, kingmustard said:

Pressure-optimised or airflow-optimised fan for rear exhaust?

You'd typically want airflow for case-fans and static pressure for heatsinks and radiators, just like Noctua's page says as well.

[leclod]

The whole Airflow/Pressure discussion is flawed.

I bet you won't see any difference between your old good fan and your new good fan.

No good fan is twice as efficient with airflow than another at the same speed.

Anyway go for the Noctua NF-F12 PWM because at least it spins faster if your system lets it reach that speed.

 

Edit :

Just noticed the slower noctua fan has supposedly higher airflow and I'm wrong with some.

 

[RejZoR]

You'd need more than 1100 RPM. But be aware that having fast exhaust fan means you'll have a lot of noise coming out of the case rear.

 

Those Pure Wings 2 are just not fast enough. Something like this would be better:

https://www.bequiet.com/en/casefans/617

https://www.arctic.de/en/F12-PWM-PST/AFACO-120P0-GBA01

https://noctua.at/en/nf-p12-redux-1700-pwm

https://www.blacknoise.com/site/en/products/noiseblocker-it-fans/nb-blacksilent-pro-series/120x120x25mm.php

 

I'm using 1600 RPM Silent Wings 3, but in 140mm flavor for exhaust and while it can move quite some air, but it gets quite noisy. The thing is, that 1100 RPM fan is slow and you can't do anything about it. Which is why I recommend tasking a faster fan. You can always limit its speed, but you can't make one go faster than what it's rated for. A 1600 RPM fan you can still limit to 1200 RPM. 1100 RPM fan will always be only 1100 RPM fan.