I needed to set the CPU to constant clock speed to get correct clock measurements. Then, I realized it works more stable if I do it and turn of turbo boost for some reason (at least on Fedora 40). This post explains how to set the clock speed .

Setting CPU Speed

cpupower frequency-set -u 3000mhz
cpupower frequency-set -d 3000mhz

TODO

This didn’t work, but they say you can use it when you either disable secure boot, or this link.

Setup

sudo dnf install msr-tools kernel-tools

Learn Base Frequency

sudo dmidecode

Shows:

Processor Information
	Socket Designation: U3E1
	Type: Central Processor
	Family: Core i7
	Manufacturer: Intel(R) Corporation
	Signature: Type 0, Family 6, Model 183, Stepping 1
	Flags:
		FPU (Floating-point unit on-chip)
		VME (Virtual mode extension)
		DE (Debugging extension)
		PSE (Page size extension)
		TSC (Time stamp counter)
		MSR (Model specific registers)
		PAE (Physical address extension)
		MCE (Machine check exception)
		CX8 (CMPXCHG8 instruction supported)
		APIC (On-chip APIC hardware supported)
		SEP (Fast system call)
		MTRR (Memory type range registers)
		PGE (Page global enable)
		MCA (Machine check architecture)
		CMOV (Conditional move instruction supported)
		PAT (Page attribute table)
		PSE-36 (36-bit page size extension)
		CLFSH (CLFLUSH instruction supported)
		DS (Debug store)
		ACPI (ACPI supported)
		MMX (MMX technology supported)
		FXSR (FXSAVE and FXSTOR instructions supported)
		SSE (Streaming SIMD extensions)
		SSE2 (Streaming SIMD extensions 2)
		SS (Self-snoop)
		HTT (Multi-threading)
		TM (Thermal monitor supported)
		PBE (Pending break enabled)
	Version: Intel(R) Core(TM) i7-14700K
	Voltage: 1.0 V
	External Clock: 100 MHz

There you have external clock 100MHz. So, if you want to have a speed of 3GHz, you can set multiplier as 30. I only care for core 16 in my system. You can check the current multiplier using this (this might depend on the CPU!):

# I only
sudo rdmsr --bitfield 15:8 -p 16 -d 0x199

problem is here, permission denied…