New Latitude 5491 High Fan on AC Power. Seems clock related

I'm also experiencing a loud fan noise but in my case the clock speed actually goes down to 800 MHz.

When the laptop is under heavy load the fan runs at maximum speed (ca. 5000 rpm) and the temperatures rise up to 98 °C (according to lm-sensors).

Sometimes it takes some minutes until the fan speed decreases again. Most of the time the fan runs at 3500 or 4200 rpm when doing some work (mostly Web development). But the fan noise is pretty annoying.

Another issue is that the fan sometimes stops for a second and then returns to the previous speed.

My Latitude 5491 has a Intel® Core™ i7-8850H CPU and runs Ubuntu 18.04 (Linux Kernel 4.17.3).

I noticed that when I am running heavily intensive multithreaded compilations, the clock will randomly drop down to 800~ mhz and the machine basically freezes intermittently.

See attached screenshot. Notice load at 75%, and the clock at 797.54MHz. 

Also take note of max temps.

I know the processor has a base frequency of 2.60GHZ, when plugged in, it rarely drops below 3GHZ at idle/low loads, I believe that is part of the reason the fans are running to keep the temps in check. 

Is dell aware of this issue? Is there a bios fix in the works? I hate dropping almost $3k on a machine that hasn't been vetted or working right for power users. 

Have just got 3 of these for work. 5491 specced with Thunderbolt and the i7-8850H.

When plugged in to the TB16 dock, the fan spins somewhere between 70-100%

When plugged into power or on battery it drops back to silent unless under load.

In the diagnostics on the dock its slowest speed is 4300rpm, on battery or AC its 2400rpm.

Thunderbolt port area gets warm, but the rest of the laptop is code. Coretemp shows CPU only at 40 Degrees Celcius but the fans going loudly.

I've logged this with dell, and all drivers and firmware are upto date for both the laptops and docks.

Fingers Crossed for a bios fix.

Exact same here. Dell has been quite about it. I'm starting to wonder if the laptops have poor cooling solutions for the high power micros.

I dont believe its the CPU, mine never goes over 50-60 degrees.

More inclined to think its the thunderbolt chip, as just plugged into AC we dont have this issue.

Swapped my TB16 dock over to a WD15 and my fan noise is gone!.

must be thunderbolt related!

I'm using a WD15 but still having that issue. Which firmware is installed on your docking station?

It happens anytime the machine is plugged in on AC. Regardless of dock or actual AC adapter.

We have 28x Latitude from 5550 to 5580 here. 12 of them are with discrete GPU for Dell Thunderbolt Dock TB16 (we like them very much). None of them have fan issues. But the 2 last are 5591 and fan noise is out of control for both.

all drivers up to date, TB16 fully updated on laptop (There is a BIOS for TB16 I can't seem to update though?). Dell Command | Power manger installed on both and configured  for "Silence" mode...  Small improvement, but not enough...

Waiting for dell update....

Hmm we have the same, I opened a ticket with Dell.

Let us know what they say. 

Seems like this might be related and the issued a bios update https://www.dell.com/community/Latitude/Dell-7480-and-Dell-5480-fan-noise-and-heating-issue-on-more-than/td-p/6072570

Dell can we get an official response? 

The other topic seems related to 5480 / 5580. With 10 of those, they are now indeed more silent than ever.

But 5591 (and 5491) are still a problem on my side.

Thanks for the link!

@Dell-Alan D are there any news on BIOS updates for the 5491 / 5591 series? Working in the office with the fans running at full speed is actually quite disturbing.

By the way, I have SpeedFan installed and it shows the fans are already running at full speed when the CPU temperature is only at around 60° Celsius. I think Intel allows up to 100°C - so it is definitely a software issue.

To mitigate the issue I've bought a laptop cooling pad and now I have times when the CPU is at 40°C and the fans are still running on full speed :Hmm:

Hi,

I have installed Dell Power Manager ( turned it in quiet mode ) and connect a WD15 dock, fan still blows but I think at 20% so better but not solved!

Hi all, 

Thanks for reaching out to us about the fan issues. Engineering have advised that there is a new BIOS revision currently in development and should be released in the next few weeks.

Alan