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How to enable C-States on Xeon W-1290P


I am running a Intel 10th Gen Xeon W-1290P Comet Lake CPU]. The CPU is really similar to the normal desktop i9-10900k.

The machine containing the CPU runs a Proxmox Hypervisor with Linux kernel 5.11.

root@server:~# uname -a
Linux server 5.11.21-1-pve #1 SMP PVE 5.11.21-1~bpo10 (Wed, 02 Jun 2021 11:34:45 +0200) x86_64 GNU/Linux


Energy usage is important to me, so I tried to verify that my system uses C-States to save as much power as possible. While investigating, I found that my system does not use any C-States deeper that C3.

I wanted to find out why my system does not use deeper C-Sates, such as C6, C7 and so on.

Querying sysfs for the max_cstate shows a value of 9.

root@server:~# cat /sys/module/intel_idle/parameters/max_cstate


Using the cpupower utility, I got some additional information on the available C-States.

root@server:~# cpupower idle-info
CPUidle driver: intel_idle
CPUidle governor: menu
analysiere CPU 0:

Number of idle states: 4
Available idle states: POLL C1_ACPI C2_ACPI C3_ACPI
Latency: 0
Usage: 1012041
Duration: 3293515
Flags/Description: ACPI FFH MWAIT 0x0
Latency: 1
Usage: 1340146
Duration: 215843217
Flags/Description: ACPI FFH MWAIT 0x33
Latency: 151
Usage: 949495
Duration: 949112994
Flags/Description: ACPI FFH MWAIT 0x60
Latency: 1034
Usage: 315636
Duration: 1552349782


Running cpupower idle-info clearly shows, that intel_idle is used as the idle driver. Strangely, it also shows that my system only supports 4 idle states, and they are named C1_ACPI, C2_ACPI, ... instead of C1, C2 and so on.

I also verified that my system uses intel_pstate as the scaling driver.

root@server:~# cpupower frequency-info
analysiere CPU 0:
driver: intel_pstate
Folgende CPUs laufen mit der gleichen Hardware-Taktfrequenz: 0
Die Taktfrequenz folgender CPUs werden per Software koordiniert: 0
Maximale Dauer eines Taktfrequenzwechsels: Cannot determine or is not supported.
Hardwarebedingte Grenzen der Taktfrequenz: 800 MHz - 5.30 GHz
mögliche Regler: performance powersave
momentane Taktik: die Frequenz soll innerhalb 800 MHz und 5.30 GHz.
liegen. Der Regler "powersave" kann frei entscheiden,
welche Taktfrequenz innerhalb dieser Grenze verwendet wird.
current CPU frequency: Unable to call hardware
current CPU frequency: 4.90 GHz (asserted by call to kernel)
boost state support:
Supported: yes
Active: yes


Why is my system not supporting deeper C-States, like C6? Is there anything I can do to change this? Why are the C-States named C3_ACPI instead of C3 on my system?

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1 Reply

Hello naglerrr,

Thank you for joining the Intel community

In regards to your question, we would like to encourage you to post the technical information you are looking for in the following community site: .

They can help you with additional questions about Intel Xeon W Embedded Processors.

Also, if you already know the FAE ( Field Application Engineer ) that corresponds to you, you can contact them to gather more details.

Have a great day.

Jose A.

Intel Customer Support Technician

For firmware updates and troubleshooting tips, visit: