Limited CPU C-States (£C3_ACPI) on DeskMini B760

Hello ASRock Support Team,

I'm reaching out for technical support regarding an issue with limited CPU C-States on my setup:

Hardware:

Mainboard: DeskMini B760

CPU: Intel Core i5-14600T (Raptor Lake, 14th Gen)

Software Environment:

Operating System: Proxmox VE 8.2 (Debian 12 based)

Linux Kernel: 6.8.12-10-pve

Microcode: intel-microcode 3.20250211.1~deb12u1

Observed Behavior:
Using PowerTOP and cpuidle drivers on Linux, I can only observe C-States up to C3_ACPI. Deeper idle states like C6, C7, or C10 are missing. In PowerTOP's "Idle States" tab, all entries are suffixed with "_ACPI" indicating the C-States are sourced purely from the ACPI tables and not via Intel-native mechanisms.

Tests and Verifications Done:

Verified BIOS settings: "CPU C-States" are enabled.

Verified "Enhanced Halt State (C1E)", "CPU C6 State", "CPU C7 State" and "Package C State Support" are all enabled.

"/sys/devices/system/cpu/cpuidle/current_driver" shows intel_idle, meaning the kernel is using the correct driver.

Kernel parameters used:

intel_idle.max_cstate=9 processor.max_cstate=9

Powertop autotuning applied and persistent.

ACPIDUMP analysis: ACPI tables only list _CST entries up to C3, no higher C-States are defined.

Root Cause Analysis:
After extensive analysis, it appears that:

The BIOS/UEFI firmware only advertises C3 as the deepest possible idle state.

No deeper C-States (C6/C7/C10) are presented to the operating system.

Therefore, the CPU cannot enter the deep sleep states needed for maximum power efficiency.

Impact:

Increased idle power consumption.

Missed opportunity for the system to operate in ultra-low-power states.

Questions to ASRock Support:

Is this behavior expected by design for the DeskMini B760 with 14th Gen CPUs?

Are there hidden or undocumented BIOS settings (e.g., Low Power S0 Idle, Package C-State Limit) that can unlock deeper C-States?

Could a future BIOS/UEFI update enable deeper idle states?

Is there any workaround you can recommend to enable support for C6/C7/C10 package states?

Additional Notes:

This issue is not related to operating system or kernel support; it is purely due to ACPI/firmware limitations.

I am aware of similar behavior reported for other ASRock boards where BIOS modifications or AMISCE tools were needed to unlock hidden settings.