Question Lian Li Uni-Fan P28 Controller question ?

[Assaf Patishi]

Hi everyone,
I just bought a bunch of these fans. With the pack of 3 you also get a fan controller with 3 modes (Low 300-1300 , Medium 300-2200 , High 300-2600) . Unlike normal fan controllers that I've used in the past, where you have a Sata power connection directly to the PSU, this controller connects to a fan header on the motherboard instead.
If I understand correctly this "controller" is more like an RPM limiter, so that means I can set it to the desired position and change the speed of the fan within this range? (e.g 100% will the 2200 RPM in the Medium setting, and 1300 in the Low setting etc.)

Can someone confirm this? I don't think I would ever want it to operate at 2600 RPM so limiting to 2200 is appealing to me.

EDIT: I was wondering if the whole RPM range is affected or just the maximum speed? For example, if the max RPM for these fans is 2600 RPM, so in High mode the 50% is 1300.. what about the Medium setting? will it now be 1100?
Hope I explained myself clearly

 

[Lutfij]

Specs page says it's 12v;

UNI FAN P28

<ul> <li aria-level="1">Noise-optimized and performance-oriented fan</li> <li aria-level="1">FDB Bearing with copper shielding to ensure stable rotation of the impeller</li> <li aria-level="1">Liquid crystal polymer fan blades to ensure tight tolerance</li> <li aria-level="1">Toggle...

lian-li.com

that would lean into the controller taking that power from the board and then allowing you to manipulate the voltage using said controller.

I would however be wary of the 6 fans mention, since a fan header on the motherboard might only be rated for 1A, which comes roughly to 3 fans.

 

[Paperdoc]

The info on the Lian Li web pages indicates that all the 3-speed switch does is reduce the speed of the fans so they run slower than they should for any given signal from the mobo header. It indicates that this does not affect their minimum speed (so they will not stall), but does reduce speed over the entire range. I recommend you do NOT use this, and set the switch to full speed.

Why? The system gets power AND the speed control PWM signal from a mobo header. But what the header is doing is NOT speed control. It is TEMPERATURE Control - it uses a temperature sensor on the mobo and decides to manipulate the speed of the fans to achieve a temperature target. It does this with a control strategy called Feed-Forward. That is, for any measured temperature value it calculates a fan speed that should be able to keep the temperature stable there. IF the temperature changes due to workload or whatever, the speed decision changes. In your case, OP, if you set the switch to a lower speed range, whatever the mobo header decides is the right fan speed to get the right air flow for cooling, the slowed-down fans will NOT deliver that air flow, and the temperature at the sensor will continue to rise. So the header will raise the fan speed signal to get more air flow. This will continue until the temperature is high enough that air flow finally keeps it from rising further. The result is that the mobo is prevented from going too hot, but it is now operating at a HIGHER temperature than the header originally intended. Moreover, if your workload gets very high, at some point the fans are NOT allowed to go to their maximum cooling ability and they may NOT be able to prevent overheating!

On the other hand, if you leave the switch set to max speed, the mobo header WILL actually reduce the fan speeds to whatever really is needed to keep the mobo cool and will adjust that as the workload changes. This WILL give you quiet fan oeration at lower speeds while guaranteeeing that they will be able to provide their best cooling under all conditions.