HP Switch

I wanted to replace the stock fans in my HP 2810-24g from the noisy stock ones from (Nidec?) to proper silent ones from Noctua, namely their amazing NF-A4x20 FLX running at DC12V @ 0.05A (0.6W) But my first attempt gave me a “FAULT” status and loads of errors in the event log. But I fixed it, here’s how:

See, most fans nowadays have 3 Pins:
RED – DC Voltage +
BLACK – DC Voltage –
YELLOW – Tachometer

Here the yellow wire is to detect a fault. Namely, if the yellow wire isn’t grounded the switch assumes there’s a fault. Fortunately, this is an easy fix!

Installing the fans

This part is by far the simplest, use a Phillips screw driver, remove the old screws and the old fans will just get loose, take them off the case. Remember to save these screws and fans in case you wanna revert to stock. One more thing to note, the screws the stock switch fans use aren’t thick enough for these Noctua fans, use the ones that come in the Noctua packaging! Lastly, remember to get a different bit on your screwdriver for these as they’re slightly bigger than the chassis screws.

Pardon the dust, this old bat has seen some stuff

Make sure as well to have the label on both fans facing inward, so they blow air INSIDE the switch.

Tricking the switch

Now, find an led, or a resistor, or a clip, anything metal that is about the size of the fan pins. We’re about to make a dirty jumper! Now:

  • Remove the yellow wire from the connector
  • Insert the pin between the black connector and where the yellow one was. MAKE SURE YOU REALLY PRESS IT DOWN, you want it to connect GND (Black) to where the yellow connector was
  • Isolate the yellow wire (cut it, tape it up, or shrink tube it), you don’t want this to potentially short something.
as you can see, a small metal pin jumping ground to where yellow was. I also used some yellow heat shrink tubing to isolate that pin just in case. As a reminder, this pin solely reports the RPM Value from the fans, this switch does not use it.


To make sure both of your fans are working correctly, power on your switch and see if the FAULT LED turns on. Should a fault be detected, maybe it’s time to check your event log and see which one is failing and try again. You can usually do this by Telnet-ing to the device ([FTP]Here’s a copy of the manual if you’re interested ) and running the “menu” command then choosing “Event Log“. The event log will gladly tell you which one is failing. Using this information, tweak your jumper job until she’s happy.


Purring like a kitten, ready to serve!

After its power on self-test she reports no fault. Both fans are spinning and quiet, which was the whole point of this upgrade.

Proceed to close up and admire your handiwork:

Isn’t she lovely?

I hope this helps you since I spent hours trying to figure this out!