0
I often see, in the performance monitor, CPU speed varying according to CPU utilization: When utilization increases speed increases:
However sometimes this relationship is inverted: Speed increases when utilization decreases:
On the image above, most of the time CPU is decreased for load peaks, but the direct relationship restarts for the last quarter of the graph. It seems this happens below a certain "load" value. If that matters, when the CPU is fully used (with the current power management settings) frequency is at some intermediate level:
What is the technical explanation for how speed is managed, and how power selected management strategy is taken into account here?
Reference to Intel or general documentation preferred to guesswork ;-)
Questions I have read before asking:
- Task manager: CPU Utilization and speed?
- CPU Utilization in Task Manager
- What is CPU utilization and how is it calculated, how does OS scheduling work?
Using W7 on Lenovo W510 (720 QM, i7 family).
From your link, I found a press article about Turbo Boost (it was TB 1.0 on the Clarksfield generation) which can explain why clock frequency is high when load is low: "when the four cores aren't running a worst-case workload [...] Turbo Boost can increase the frequency of all four cores until they're running as fast as they can for the current workload". CPU would be more efficient at some relatively high frequency, but this is limited by the thermal impact (high use).
– mins – 2018-08-26T12:02:46.563The hardware tries to lower power consumption by regulating the frequency/voltage. The OS may also park unneeded cores. – harrymc – 2018-08-26T12:55:28.323