system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how does a monitoring software know the clock speed, data transfert etc. of components at any given time (CPU/GPU/disk/...)?
gpt
Sometimes, the monitor will show what the component itself is reporting. The component knows it is using a certain amount of power, or is performing operations at a certain rate. The driver allows for the monitor to request and interpret this data.

The monitor may also request data from the motherboard, which can control voltage or report bandwidth.

Other times, the monitor will measure this with the help of the operating system, as it is doing its own monitoring.

Some utilities may measure by testing the component, such as timing how long it takes to do a certain task. This is different from merely asking for a report, and takes more effort.