Identical Fans, Separate speeds? (by ~200RPM)

Aleksbgbg · February 17, 2016

I have 2 intake Corsair AF140 Quiet, one is spinning at 800RPM and the other at 1000RPM (both set to full speed)

One of them has an extension cable (came with fan) attached, however I don't know which one - do you think this would be slowing it? Their cables and the extensions are all 3 pin.

Other ideas to fix this?

Mattyd7829 · February 17, 2016

I think maybe that the cable is a low noise adapter, not an extension cable. This cable reduces the fans speed to combat noise.

Aleksbgbg · February 17, 2016

Just now, Mattyd7829 said:

I think maybe that the cable is a low noise adapter, not an extension cable. This cable reduces the fans speed to combat noise.

Shit.

Wow I never thought of that, I honestly needed like 1cm to reach so I put it on. Thanks, I'm gonna remove it now and route the cable differently.

NeoFrux · February 17, 2016

Yup, definitely sounds like you're rocking an LNA. Those cables have resistors in them to reduce the 12V input power down to 7V or 5V (probably 7V in this case). Usually you'd only want to use those for non-PWM fans, and fans that can handle running at the slower speeds. Noctua coolers in particular usually come with a 7V and a 5V (called LNA and Ultra LNA respectively).