You'll most likely be able to solve your problem with something else overriding your i8kctl fan commands by the method given in this answer. For completeness, I'll include some general notes on fan control on Dell laptops, and full instructions for
What probably won't work
Two common and straight-forward means of controlling the fan on laptops are through ACPI and through PWM pins, however, unfortunately:
Dell laptops lacks ACPI fan control capability (*1)
- as a consequence, trying with ACPI boot parameters and the like will fail
Dell Latitude laptops, as far as I know, lack pwm controllable fans (*2)
- as a consequence, the
pwmconfig program won't work
However, there's a package called
i8kutils that is written to control the fan on Dell Inspiron laptops through SMM BIOS. Several users report success on their Dell Laitude laptops as well (I'm one of them, on a Dell Latitude E7440) - however, a trick is often needed to get rid of interfering BIOS fan control. You suffer from that as well according to a previous comment.
$ sudo apt-get install i8kutils
$ i8kfan 2 2 # set to max speed
$ i8kfan 0 0 # set to 0 speed
...and listen to see if it works.
Disable BIOS fan control
If it works, but somewthing else is fighting back on the setted speed (reported by many users on Dell Latitude laptops), this is due to scheduled SMM sessions setting the fan speed back. Luckily there is a way to disable BIOS fan control by writing to SMM registers.
Warning: see the warning in top of smm.c. This method will write to SMM registers. However, I've seen no user reports on this causing trouble. Also, all reports on trying this have indicated success in disabling the BIOS fan control.
i8kutils includes the source of a program
smm but the
i8kutils package does not include the compiled binary. What we'll do is to download the source code of
i8kutils, compile the program
smm, and run it with an apropriate argument to disable BIOS fan control by writing to SMM registers.
Download packages needed for building:
$ sudo apt-get build-dep i8kutils
i8kutils source code, extract and enter directory (exact names depending on i8k version):
$ apt-get source i8kutils
$ tar xvf i8kutils_1.33.tar.gz
$ cd i8kutils-1.33/
smm with argument
30a3 to disable SMM fan control:
$ sudo ./smm 30a3
Now, BIOS fan control should be disabled. Try by setting speeds with
i8kctl, listen for the fan and make sure the speed persists.
Note: This is a setting that will persist reboots and power-off's. BIOS fan control can be enabled again with
$ sudo ./smm 31a3.
*1: I've seen an official source on this, can't find it right now. If you want to verify that your hardware lacks it, follow instructions here: https://wiki.ubuntu.com/DebuggingACPI
*2: for verifying this, run pwmconfig:
sudo apt-get install fancontrol,
sudo pwm-config will tell if a pwm-capable fan is present or not