Why does an AiO cooler pump have an RPM measurement?

[King Mustard]

I've bought an AiO CPU liquid cooler and it comes with two fans.

Motherboard connector: CPUFAN1

• Liquid cooler fan #1
• 120mm EK-Vardar F4-120 (2200 RPM)
• PWM, motherboard "Smart mode" controlled / around at around 430 RPM on idle

Motherboard connector: CPUFAN2

• Liquid cooler fan #2
• 120mm EK-Vardar F4-120 (2200 RPM)
• PWM, motherboard "Smart mode" controller / around at around 0 RPM on idle

Motherboard connector: SYSFAN1

• The OcUK Tech Labs 240mm liquid cooler itself

My motherboard is telling me that SYSFAN1 is running at around 1500 RPM.

Where is it getting that number from?

 

[Hotwired]

Because that's how fast the pump is spinning.

It's just another brushless DC motor like the fans and its RPM can be measured.

 

[King Mustard]

Because that's how fast the pump is spinning.

It's just another brushless DC motor like the fans and its RPM can be measured.

Ah, I see!

I didn't really know what went on inside that little block

 

[Alexrose1uk]

It also means you can see if the pump has failed