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ZeroAviation
1 Nickel

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

Hi,

I just got a new 5491 this week. When on AC power, the fans seem to run at a high rate all the time. (Which is annoying in a quite office).

Here is what I have noted

On AC power, clock never goes below 1.8GHZ-2.5GHZ, which causes temps to idle around 50C and the fun runs at (guessing) 75%. If I were to compile a project, fans go to full tilt almost instantly, and don't come back down to 75% for some time. It sounds like my laptop is about to take off. 

On battery, clock idles around 800mhz-1GHZ, and you can barley hear the fan. Compiling the project, the clocks and temp rises, fan kicks up a tad, then goes back down when complete.

Pretty sure this is a bios issue with clock control and power source. Not sure if this is the proper channel to submit such a bug, being a new machine and all.

 Machine has a i7-8850H, basically it's a fully optioned setup.

Thanks

 

97 Replies
Traini
1 Copper

Re: New Latitude 5491 High Fan on AC Power. Seems clock rela

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).

dell-5491-high-fan-speed-and-temperatures.png

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).

ZeroAviation
1 Nickel

Re: New Latitude 5491 High Fan on AC Power. Seems clock rela

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.Issue.png

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. 

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Lordz89
1 Copper

Re: New Latitude 5491 High Fan on AC Power. Seems clock rela

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.

 

 

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ZeroAviation
1 Nickel

Re: New Latitude 5491 High Fan on AC Power. Seems clock rela

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.

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Lordz89
1 Copper

Re: New Latitude 5491 High Fan on AC Power. Seems clock rela

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.

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Lordz89
1 Copper

Re: New Latitude 5491 High Fan on AC Power. Seems clock rela

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

must be thunderbolt related!

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Traini
1 Copper

Re: New Latitude 5491 High Fan on AC Power. Seems clock rela

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

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ZeroAviation
1 Nickel

Re: New Latitude 5491 High Fan on AC Power. Seems clock rela

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

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Fredtheboots
1 Nickel

Re: New Latitude 5491 High Fan on AC Power. Seems clock rela

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....

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