I spent some time this morning trying to work out why my CPU - the beastly Intel i9 7980XE - was capped at 2.6ghz when the BIOS allows scaling to 4.3ghz. When I ran the usually suggested cpufreq and cpupower commands, I received: “no or unknown cpufreq driver is active on this CPU”. The reason for this was that you need, in the UEFI/BIOS, to enable: Intel Enhanced SpeedStep and the option to expose pstates.