I'm rebuilding a PC from parts of several older systems and am using an MSI motherboard with an Intel Core i9-11900K. The computer runs normally, but during testing the CPU stays at relatively high frequency and temperature even when it is idle. I currently have the power limits set to 175 W long-term and 250 W short-term, but power usage does not seem to fall below 175 W at idle, and the clock speed rarely drops below about 4.9 GHz.
Shouldn't the processor reduce its frequency and voltage when idle, reaching something closer to its base clock or lower? Also, when I run a single-core benchmark, all the cores appear to increase to similar speeds. I expected one or two preferred cores to boost higher while the others stayed lower.
I'm more familiar with AMD systems, where idle power generally drops and single-threaded workloads boost specific cores. Is there an MSI BIOS, Windows power-plan, or Intel setting I should check?
3 Answers
Check your Windows power plan first. Ultimate Performance can keep the CPU near its maximum turbo frequency and voltage instead of allowing normal idle downclocking. Switching to the regular Performance plan and lowering the minimum processor state should let the clocks and power usage fall when the system is idle.
Make sure the MSI BIOS is current, then load optimized defaults and verify that CPU C-states are enabled. Disabling C-states or applying an all-core overclock can prevent the processor from entering low-power idle states. After that, reapply only the settings you actually need, such as XMP, fan curves, and power limits.
I wasn’t intentionally applying an all-core overclock; I only changed the long and short power limits. I set them to 175 W and 250 W because the tower cooler should handle more than the stock 125 W specification. I also reset the BIOS while troubleshooting memory settings, although my attempts to run the 4000 MT/s kit at 3600 CL16 or 3333 CL16 were unsuccessful.
The 11900K can run hot, but it should still reduce voltage and frequency at idle when the operating system and BIOS allow it. Check the Windows processor minimum state, MSI’s CPU power-management options, and whether C1E/C-state support is enabled. For single-threaded workloads, Intel’s preferred-core behavior may not be obvious if the benchmark briefly schedules work across several cores, so use a monitoring tool that shows per-core clocks and effective clocks rather than only the maximum reported frequency.
That was the issue. I had enabled Ultimate Performance while tuning stability and thermals, and it was keeping the processor at maximum turbo and voltage. After switching plans and lowering the minimum percentage, the system became cooler and quieter, and the clocks started dropping properly. The short-term power limit also began working as expected. I also tried a small undervolt, but this chip does not have much undervolting headroom.