I use a PicoPSU-like solution with a 120W external adapter. Sometimes the i5-9400F PC consumes up to 96W. I feel uncomfortable about it and decide to lower power consumption by setting a new turbo frequency limit.
Monitor CPU Frequency
To monitor CPU frequency and refresh every 1 second:
$watch -n 1 "cat /proc/cpuinfo | grep MHz" Every 10.0s: cat /proc/cpuinfo | grep MHz i5-9400F: Sat Jul 9 20:51:25 2022 cpu MHz : 900.000 cpu MHz : 1095.972 cpu MHz : 800.000 cpu MHz : 800.000 cpu MHz : 800.000 cpu MHz : 800.000
To increase the update interval to every 2 seconds, change ‘1’ to ‘2’. To decrease to 0.1 seconds, change ‘1’ to ‘.1’.
Customize Turbo Boost Frequency
In Gigabyte H310M S2V 2.0’s BIOS menu, open the [MIT] tab ➞ [Advanced Frequency Settings] ➞ [Advanced CPU Core Settings] page. Assign new integer values in the Turbo Ratio options.
To decrease the upper limit for 400MHz on i5-9400F, update the “Auto” field as below:
|Turbo Ratio (1-Core Active)||37||41|
|Turbo Ratio (2-Core Active)||36||40|
|Turbo Ratio (3-Core Active)||36||40|
|Turbo Ratio (4-Core Active)||36||40|
|Turbo Ratio (5-Core Active)||35||39|
|Turbo Ratio (6-Core Active)||35||39|
Better Power Control
(Default up to 4.1GHz)
(Customize up to 3.7GHz)
|Max Power consumption||96W||77W||60W|
Decreasing the upper limit for 400MHz helps to manage the max power consumption within 77W. While the CPU runs 600MHz to 800MHz faster than the base 2.9GHz, it is still 19W lower than the default Turbo settings. I think this is a good balance. There is no need to disable Turbo Boost to save power in this case.
For notebooks, Joel found that “Disabling Intel Turbo Boost Has a Huge Impact on Battery Life”. It is because that “…Clearly, turning on Turbo Boost exacts a power consumption penalty…” and “…power consumption increases significantly under load when you augment clock rate and voltage…”.
Also, “…Turbo Boost is most effective at improving the performance of poorly-threaded applications…”. If it cannot accelerate programs with acceptable power usage, consider lowering the turbo limit or disabling it.
- LinuxHint: How Do I Find CPU Frequency in Linux?
- Software Engineering Authority: How to get CPU Frequency in Linux
- die.net: watch(1) – Linux man page
- Tom’s Hardware: Experiment: Does Intel’s Turbo Boost Trump Overclocking? Page 10: Power Consumption
- Tom’s Hardware: Experiment: Does Intel’s Turbo Boost Trump Overclocking? Page 11: Conclusion
- HardwareTimes: Intel 11th Gen Rocket Lake-S CPU Power Consumption Explained
- ExtremeTech: Disabling Intel Turbo Boost Has a Huge Impact on Battery Life