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

I apologize if this message goes twice, but not seeing first one.  We have a brand new 5491 that got its new Thunderbolt docking station on Monday, 7/30 and simultaneously prompted to update the Bios.  Since then, fan is running constantly.  Don't know if it is the bios or docking station as both happened together.  And wondering if the bios we were prompted to install on 7/30 was the one you mentioned was coming in a few weeks or was an interim one.  Hoping one is still coming.  Please advise on that and, in the interim, any advice so we don't ruin the new laptop we have spent a long time configuring?  Thank you.

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@Churchlady1 wrote:

I apologize if this message goes twice, but not seeing first one.  We have a brand new 5491 that got its new Thunderbolt docking station on Monday, 7/30 and simultaneously prompted to update the Bios.  Since then, fan is running constantly.  Don't know if it is the bios or docking station as both happened together.  And wondering if the bios we were prompted to install on 7/30 was the one you mentioned was coming in a few weeks or was an interim one.  Hoping one is still coming.  Please advise on that and, in the interim, any advice so we don't ruin the new laptop we have spent a long time configuring?  Thank you.

 

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Hi @Churchlady1, the cpu fan will spin more than usual whenever the system is connected to the docking station. This is the system working as designed. As long as the dock is connected the fan will be behave as it is.

If when you disconnect the dock the fan constantly spins, it could be based on the power profile you are using. You could try changing to quiet mode to reduce the fan noise on the system. These issues should be addressed by the revised thermal tables in the up and coming BIOS.

Alan

I wanted to order a 5491 with i7-8850H and Thunderbolt but I will wait for a solution to the fan issue and meanwhile I'll look for alternatives. The last thing I need is that the fan is running 24/7.

Bios update 1.3.8 has made matters worse. 

Now the CPU hits PROCHOT a lot more often and the clock is reduced down to 700~MHZ During high workloads. This is almost unusable when doing actual work.

What are we as the end user supposed to do?

75% load, and the clock is at 797MHZ. Unusable

It could also be the latest Windows Feature + BIOS Updates, as a couple of new Latitudes (7 8 and 9 series) at work started screwing up in a similar manner (run hot, fan on 90% of the time, etc.) and it turned out to be a power driver issues after the latest Win 10 and Dell BIOS updates.

The CPU was apparently running at full voltage (even when it lowered clock speeds) and it took some reinstalling of drivers, including some vendor updates, to get rid of all the issues. The common denominator was constant fan activity + higher heat production than usual + power function issues like the loss of Sleep or Hibernate features.

On one of them, I booted it back and up recently and all the power functions suddenly started working and there was no fan and the exhaust + bottom of laptop were as cool as a fridge. It stayed that way for half an hour until the fan slowly and near-silently started up.

Trust me, there is some very bad stuff going on with all these BIOS updates for security patches and the latest Win 10 Feature and Security updates and this may be at least part of your problems.

Another issue I wanted to add is that if Win 10's "Fast Startup" is enabled, you might want to disable it and physically restart to make sure that Windows 10 fully recognizes all the BIOS and system changes.

This was one of the problems we ran into, that these Fast Startup systems literally hadn't been physically rebooted in a long time (they just go into hybrid-hibernate when shut down), and when we turned off Fast Startup, the reboot took a few minutes, and after hitting the BIOS for probably the first time in weeks, things got a lot better from a power management/fan noise/CPU heat scenario.

What is most amusing about this whole scenario is that we also discovered that enabling "Fast Startup" on our NVMe SSD systems took *longer* to startup and reload the old hiberfil.sys file compared to simply cold booting the regular way.

Yup, that's the issue to a tee. 

Dell, can we get a response? 

I have all those updates. See my post from end of page 2

Dell?

bunch of updates came out on the 15th seems to fix the issue.  Clock now drops down to 1ghz when idle.

I have received my latitude 5491 few days ago, and as many of us I was very disappointed by the noise and the heat of the laptop. So I’ve take a day to understand the source of this issue and I have some interesting results to share.

First of all, I’ve done all my test under Windows with my latitude 5491 and the 5480 from a friend which share the same case and issues.

The first issue encountered is the high temperature of the CPU itself, it's not very hard to reach 98/99°C on this laptop. I have 3 ideas to mitigate the issue.

•  Under-volting (-150mv ok on my CPU)
•  Limit the CPU to 30/35 watts (the CPU no longer go beyond 90 °C)
•  Add a second heat pipe over the original? (not tested)

I ‘have use throttlestop to adjust the CPU settings.

After this tweaking, I found that the temperature of the CPU was much more acceptable, unfortunately it changes nothing about the noise. Even when the CPU was cold (45 / 50 °C). I've finally found that the fan speed is related to CPU temperature AND the thunderbolt controller temperature. 

With the CPU undervolted and TDP limited to 5 watts, the laptop is very quiet at idle when use it over battery or ac, however when I plug a device on the USB C port (razer core v2, dell WD15, dell TB16), the thunderbolt chip gets very hot and the fan start. I am not sure that running a fan at 20 cm of a chip is the good ways to cool down this chip. Another hot chip is the USB PD controller.

I didn't have a laser thermometer, but the TB controler was hot enough to burn my finger. I hope dell can give a firmware which don't start a fan located at the other side of the laptop to cool down the chip or reduce the heat produced by the chip (not sure that it is possible).

In every case, i hope that my post will help some people to understand the noise and heat issue of the laptop.

Thanks for doing the research!

So basically, this laptop doesn't have adequate cooling? 

Dell, any comment?

Hi all, 

Thanks for your continued updates and feedback on the thread. Engineering are aware of this issue and are investigating further.

As soon as there is an update I will be back in touch to advise.

Alan

Yes throttlestop is the only software that helped me to kinda solve this problem.

I now have different profiles for throttlestop.

The first one is "high performance" and still provide a fan noise (-110mV and TDP 15/25).

The second one is "mid perf" is the same as high perf and have a limitation of the maximum frequency in turbo mode.

And the third one is the same as the second with turbo mode disabled.

 Thermal design on those laptops are very bad. Even with a low power consumption CPU there is many problems of heat/noise.

I installed Latitude_5X91_Precision_3530_1.3.8.exe bios update (from August 14th, 2018) at https://www.dell.com/support/home/us/en/04/product-support/product/latitude-14-5491-laptop/drivers, and powered off and powered on the computer, and the fan seems fine now. A soft restart was not sufficient. I'm just doing light office work, and haven't done thorough testing.