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HP Recommended
HP Z840 Workstation
Linux

I have an HP Z840 Workstation.  I could not understand why the fans always ran fast. I assumed it was due to running Red Hat Enterprise Linux 7 on the workstation, but other Linux distros had done the same.

 

I recently plugged in my audio speakers into the built-in 3/8 inch jack in the back of the machine.  When I did this, the fans immediately slowed down to the normal, and quiet, speed.  I've monitored the CPUs' temps and all temps check out, even under heavy load. Under load, the fans speed up a little bit, but not nearly as much as when the speakers are not plugged in to the workstation.  So the fans all appear to be working well.

 

I have a small video of this because I don't think anyone would believe me.  I'm not sure if I can attach it here.

6 REPLIES 6
HP Recommended

That is worth knowing about, and I am sure HP would be interested in figuring this one out.

 

Could you please upload your video to YouTube?  Then you could add a post here with the link to that.

 

Thanks much!

HP Recommended

Here is a short video of the fans ramping up and slowing down with the use of an audio jack.  I can do a different video if needed.

 

This system has dual CPUs with 128 GB of RAM.  The system does not while running Red Hat Enterprise Linux 7.4 during the testing.  Not sure if it occurs with Windoze or not.

 

https://youtu.be/tLP7JpdQYa4

 

 

HP Recommended

The BIOS seems to be up-to-date with Rev 2.34.

 

It's not a big deal, but interesting.

HP Recommended

So I guess no one in HP Support or on the forums found this strange - no other replies.  Really?!

 

 

HP Recommended

if the fan speeds slow down when the audio jack is used, i suspect a resistive type short to ground somewhere

 

a direct short would cause a power off, but a short that has (say 2 k oms) resistance might only cause a voltage drop

 

that does trip the current protection

 

is the house wiring correct? (IE-proper grounding at the outlet) are all other powered items grounded?

 

 

have you tried, another audio prodect in the jack

HP Recommended

The easiest way to temporarily solve the problem is Disableing internal speaker in BIOS. To 100% solve the problem You have to replace cable that connects MB with FRONT PANEL and SPEAKER. Thermal Sensor placed inside that cable at  speaker out side. Sensor is poor or cable has bad connection between shield wires near sensor (like in my case). Hope this helps. Have a nice day!

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