Please explain what FLX and ULN?

[Zachattack3ee]

I have been researching fans and have come across these terms a few times, could someone please explain them to me? I know that they are alternatives to PWM which I know requires 4 pins and allows for variable speeds as chosen by mobo, Just don't know about the two above.

 

[Natsukage]

Hello.

This term is mostly for Noctua fans:

FLX means Flex or Flexible. It usually comes with a switch system to choose between 3 or more speeds, depending on your use, thus the "flexible" name.

ULN means Ultra Low Noise. It is essentially a FLX but with lower voltages, rotations per minute, and audible noise.

Check out this review for comparison:
http://thepcenthusiast.com/noctua-nf-s12a-pwm-flx-uln-series-review/

 

[n0ns3ns3]

it's about RPM.
the FLX comes with bunch of adapters that allow you to set the fan speed at desired level.
the ULN is ultra low noise - not recommended for the normal applications as the fan spins really slow moving very little air for most practical applications.

 

[Zachattack3ee]

Hello.

This term is mostly for Noctua fans:

FLX means Flex or Flexible. It usually comes with a switch system to choose between 3 or more speeds, depending on your use, thus the "flexible" name.

ULN means Ultra Low Noise. It is essentially a FLX but with lower voltages, rotations per minute, and audible noise.

Check out this review for comparison:
http://thepcenthusiast.com/noctua-nf-s12a-pwm-flx-uln-series-review/

it's about RPM.
the FLX comes with bunch of adapters that allow you to set the fan speed at desired level.
the ULN is ultra low noise - not recommended for the normal applications as the fan spins really slow moving very little air for most practical applications.

So then why would anyone choose ULN fan if they can choose an FLX and use the ULN adapter that is included?

 

[Natsukage]

So then why would anyone choose ULN fan if they can choose an FLX and use the ULN adapter that is included?

The ULN fans have a way lower audible noise level, even compared to the FLX with the noise reducer. (L.N.A.) If you compare in the review I gave you, the FLX has 7,4 dB(A) even with the best noise reducer (U.L.N.A.), while the ULN fan has 6,7 dB(A) with the normal noise reducer.
Of course...this is all minimal, you usually can't even hear 10db at a few feet...

Also, some people prefer less extra wiring and adapters, for a quieter build. Price can be important too.

 

[n0ns3ns3]

there are some special "cases" when a all you need is 650RPM. Some (basically most) fans can not spin at such low speed.
For example my NF-P12 fans will start spinning only when voltage reaches the level the cause them to spinn at around 800RPM. I can then slow them down even to 300RPM. So those ULN fans have special motors that can start at lower speed. 800-1000RPM on nocutua fans is moving quite a lot of air at very low noise. The 6-7db are irrelevant as this is the noise that fan produces in open air. mount it on something like radiator, heatsink or even case with grill and it will make much more than 10db. but at 800-1000RPM they (noctua) are basically inaudible from 50-100CM.