CPU temperatures in linux: throttling or wrong reading

I had a similar problem in that my firewall (an old laptop) would shut down due to CPU overheat. I used the following steps to solve the problem, valid for the pfSense firewall:

1) Download FreeBSD cpu-speed.sh file from GitHub by dreamcat4

2) Create file cpu-speed.sh, and paste contents from source linked in previous step, through pfSense management interface, using Diagnostics >> Edit File

3) Enable execution of file cpu-speed.sh in fSense management interface, using Diagnostics >> Command Prompt and the command $ chmod +x /[path_to_file]/cpu-speed.sh

4) Check available CPU frequencies by running $ sysctl dev.cpu.0.freq_levels in Command Prompt

4) Run file cpu-speed.sh [valid_CPU_frq] using command $ cd /[path_to_file] && ./cpu-speed.sh [valid_CPU_frq]

5) Check current (new) CPU frequency using command $ sysctl dev.cpu.0.freq

6) Done.

I chose the min acceptable CPU core frequency for my CPU, and was able to permanently reduce the CPU core temp of my CPU from +90 C to < 60 C.

EDIT: To avoid dead links in the future, please find the code by dreamcat4 (as linked above) for file cpu-speed.sh below:

#!/bin/sh
#
# cpu-speed:
#   Requirements - be the root user, FreeBSD 9.2 or higher.
# 
#   Get or set the CPU frequency. This command with no arguments will
#   print the current CPU frequency. CPU may be idling at it's lowest speed.
#
#   This command takes 1 optional argument - new MAX cpu freq (in Mhz).
#   expressed as an integer number. e.g. "cpu 800" - set max freq 800 Mhz.
#   This MAX figure is the new max frequency it is allowed to clock up to.
#
#   Number is rounded off to the nearest allowed frequency multiplier.
#

show_all_cpu_sysctl_settings()
{
# Most FreeBSD kernel settings are read-only. Some may look like duplicates.
# Very few are read-write (so we use powerd). Some CPU settings depend on the CPU family.

# This command should reveal all the CPU-related key names:
    sysctl - a | grep - i cpu
}

set_cpu_speed()
{
# To change the max clock, we must restart the "powerd" rc.d service 
# with new cmdline arguments. "man powerd" for more information.
    if ["$(id -u)" = "0"]; then
    if [!"$(grep "cpuspeed" " / etc / rc.conf")"]; then
       echo "" >> "/etc/rc.conf"
      echo "powerd_enable=\"YES\"" >> "/etc/rc.conf"

      # make the cmdline argument to -M flag a txt substitution with the txt file "/etc/cpuspeed"
    echo "powerd_flags=\"-M \$(cat /etc/cpuspeed)\"" >> "/etc/rc.conf"
    fi

    if ["$1"]; then
# write our new cpu speed to the txt file "/etc/cpuspeed"
      echo "$1" > / etc / cpuspeed

# restart powerd daemon to read the new cpu speed
      / etc / rc.d / powerd restart > / dev / null
    fi
  fi


}

print_current_cpu_freq()
{
# Report back the current cpu frequency for core "0"
    sysctl dev.cpu.0.freq
}

show_possible_cpu_speeds()
{
# Show a list of all possible cpu frequency steps for core "0"
    sysctl dev.cpu.0.freq_levels
}

main()
{
    set_cpu_speed "$@";
    sleep 1; # give it a chance to update before we check the new value
  print_current_cpu_freq;
    show_possible_cpu_speeds;
}

# Entry point
main "$@"

Probably your embedded controller is set to a conservative thermal setting. Note that these settings are persistent on the mainboard and not the hard disk. So if you are playing with Lenovos tools under windows, putting your notebook in a kind of "power economic & quiet" profile and then boot up ubuntu, the setting is still active.

To change this under Ubuntu, you need the right kernel module (in my case it's dell-smbios) and the smbios-thermal-ctl package to do something like this:

sudo smbios-thermal-ctl -i

 Print all the Available Thermal Information of your system: 
-------------------------------------------------------------------
Supported Thermal Modes: 
     Balanced
     Cool Bottom
     Quiet
     Performance

and then activate a more permissive profile, in my case (Dell) the best of both worlds seems to be Balanced.

sudo smbios-thermal-ctl --set-thermal-mode=Balanced

Another tool I can recommend is s-tui to diagnose such behavior.