x86intelenergymsr

Do any Intel RAPL measurements include the fan / cooling?


I am using Intel RAPL to measure energy usage of a system. On a motherboard, the fan is typically connected to the CPU for temperature control.

  1. Is the CPU fan / cooler typically powered by the CPU? That is, is the chain PSU -> CPU -> CPU fan? Or does it come from the motherboard instead and the CPU only controls the fan but doesn't power it?
  2. Do any of the RAPL power readings include this fan energy consumption?

Solution

  • I think RAPL is internal to the CPU package / silicon chip itself, thus it has no idea about current going to other things outside it which might happen to be physically connected to it.

    The CPU fan header on a typical mobo wouldn't even be pulling its 12V (PWM-controlled) supply from the special CPU-power connector; I think usually only the CPU voltage regulators are fed by that supply.