Kernel 5.8.x my system seems to be only running at it’s minimum clock of 800mhz

in think they have change driver in your case ( or you can only use intel_pstate )

in my case ( as skylake only pstate possible )

cpupower frequency-info 

analyse du CPU 0 :
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency:  Cannot determine or is not supported.
  limitation matérielle : 800 MHz - 4.20 GHz
  régulateurs disponibles : performance powersave
  tactique actuelle : la fréquence doit être comprise entre 800 MHz et 4.00 GHz.
                  Le régulateur "performance" est libre de choisir la vitesse
                  dans cette plage de fréquences.
  current CPU frequency: Unable to call hardware
  current CPU frequency: 4.00 GHz (asserted by call to kernel)
  boost state support:
    Supported: yes
    Active: yes