JanTenner

You seem to have gotten one step further. Just some thoughts. Does grep . /sys/devices/system/cpu/cpu0/cpuidle/state*/namestill show ACPI states ? (I somehow don't have pmc_core on ubuntu) Did you confirm Low Power S0 Idle (V5) : 1 in the dumped ACPI tables? Does your board have a beta firmware from ASROCK? The Z890 boards seem to have one.

1) I tried a ASRock beta firmware with a supposed fix on Ubuntu/Win11, but no success. BTW: Just saw that Lois asked for an updated status in the ASRock forum thread. 2) Tried a few SCELNX, the issue is that the relevant option is not read. Seemed to have worked on LGA1700 boards. If its Intels fault, why there some PCs which have low idle (e..g the energystar links). Also hard to believe that windows Arrow Lake laptops have the same issue. Doe really all major Z890 motherboard vendors not optimise or test this? There is ASRock, Asus, and I think also Gigabyte, MSI (no sure these two). Also not only Z890. Im just baffled that all those vendors seem to miss this. Linux and Windows. Arrow lake/LGA 1851 is not that new.

Here is the output of decoding ACPI tables, The line Low Power S0 Idle (V5) : 0 stands out. /* * Intel ACPI Component Architecture * AML/ASL+ Disassembler version 20250404 (64-bit version) * Copyright (c) 2000 - 2025 Intel Corporation * * Disassembly of facp.dat * * ACPI Data Table [FACP] * * Format: [HexOffset DecimalOffset ByteLength] FieldName : FieldValue (in hex) */ [000h 0000 004h] Signature : "FACP" [Fixed ACPI Description Table (FADT)] [004h 0004 004h] Table Length : 00000114 [008h 0008 001h] Revision : 06 [009h 0009 001h] Checksum : 64 [00Ah 0010 006h] Oem ID : "ALASKA" [010h 0016 008h] Oem Table ID : "A M I " [018h 0024 004h] Oem Revision : 01072009 [01Ch 0028 004h] Asl Compiler ID : "AMI " [020h 0032 004h] Asl Compiler Revision : 01000013 [024h 0036 004h] FACS Address : 76487000 [028h 0040 004h] DSDT Address : 762E8000 [02Ch 0044 001h] Model : 00 [02Dh 0045 001h] PM Profile : 01 [Desktop] [02Eh 0046 002h] SCI Interrupt : 0009 [030h 0048 004h] SMI Command Port : 000000B2 [034h 0052 001h] ACPI Enable Value : 00 [035h 0053 001h] ACPI Disable Value : 00 [036h 0054 001h] S4BIOS Command : 00 [037h 0055 001h] P-State Control : 00 [038h 0056 004h] PM1A Event Block Address : 00001800 [03Ch 0060 004h] PM1B Event Block Address : 00000000 [040h 0064 004h] PM1A Control Block Address : 00001804 [044h 0068 004h] PM1B Control Block Address : 00000000 [048h 0072 004h] PM2 Control Block Address : 00001850 [04Ch 0076 004h] PM Timer Block Address : 00001808 [050h 0080 004h] GPE0 Block Address : 00001860 [054h 0084 004h] GPE1 Block Address : 00001810 [058h 0088 001h] PM1 Event Block Length : 04 [059h 0089 001h] PM1 Control Block Length : 02 [05Ah 0090 001h] PM2 Control Block Length : 01 [05Bh 0091 001h] PM Timer Block Length : 04 [05Ch 0092 001h] GPE0 Block Length : 20 [05Dh 0093 001h] GPE1 Block Length : 18 [05Eh 0094 001h] GPE1 Base Offset : 80 [05Fh 0095 001h] _CST Support : 00 [060h 0096 002h] C2 Latency : 0065 [062h 0098 002h] C3 Latency : 03E9 [064h 0100 002h] CPU Cache Size : 0400 [066h 0102 002h] Cache Flush Stride : 0010 [068h 0104 001h] Duty Cycle Offset : 00 [069h 0105 001h] Duty Cycle Width : 00 [06Ah 0106 001h] RTC Day Alarm Index : 0D [06Bh 0107 001h] RTC Month Alarm Index : 00 [06Ch 0108 001h] RTC Century Index : 32 [06Dh 0109 002h] Boot Flags (decoded below) : 0000 Legacy Devices Supported (V2) : 0 8042 Present on ports 60/64 (V2) : 0 VGA Not Present (V4) : 0 MSI Not Supported (V4) : 0 PCIe ASPM Not Supported (V4) : 0 CMOS RTC Not Present (V5) : 0 [06Fh 0111 001h] Reserved : 00 [070h 0112 004h] Flags (decoded below) : 0003C6E5 WBINVD instruction is operational (V1) : 1 WBINVD flushes all caches (V1) : 0 All CPUs support C1 (V1) : 1 C2 works on MP system (V1) : 0 Control Method Power Button (V1) : 0 Control Method Sleep Button (V1) : 1 RTC wake not in fixed reg space (V1) : 1 RTC can wake system from S4 (V1) : 1 32-bit PM Timer (V1) : 0 Docking Supported (V1) : 1 Reset Register Supported (V2) : 1 Sealed Case (V3) : 0 Headless - No Video (V3) : 0 Use native instr after SLP_TYPx (V3) : 0 PCIEXP_WAK Bits Supported (V4) : 1 Use Platform Timer (V4) : 1 RTC_STS valid on S4 wake (V4) : 1 Remote Power-on capable (V4) : 1 Use APIC Cluster Model (V4) : 0 Use APIC Physical Destination Mode (V4) : 0 Hardware Reduced (V5) : 0 Low Power S0 Idle (V5) : 0

Im in the same boat as lois. Tested on windows with throttelstop and on linux with turbostat. Never reach higher than PKgC2. My theory is that intel_pstate would expose hardware states via sysfs, but it is relying on ACPI for 15th gen CPUs so no extra package states exposed. I would consider it as as interface tool. Other tools like turbostat query hardware states too. They show package states. knotgerman, you seem to be very much into the topic. Please correct me if Im understanding this wrong. It wonder what mobile variants e.g. Core Ultra 235T would do. Or is it a differently configured motherboard/bios. Can't imagine that those have the same power draw.

Im also having the C2 Package issue with a 245k on a ASRock Z890. Interesting to hear that other mainboard vendors are having the same issue. Ive tested on Ubuntu and Windows, so it seems to be a generic issue. CPU c states work fine, it's just the package state wich is stuck at C2. Someone reported on ASRock forums, that he got package states larger than C2 on Windows but not on Linux with a beta FW. I was not able to reproduce. Overall im at 22W on a barebone system with onboard LAN - not bad, not great either. I hope this gets fixed with some bios/microcode update at some point. Or someone can report at a working configuration.