How to easily undervolt 14700K with Z790-F using BIOS 2503

[Hari_Seldon]

I recently update the BIOS on my Z790-F WiFi (not II) motherboard from 2301 to 2503 and have been unable to get the system back to previous temperatures under heavy loads (compilation).  Previously, I would typically have runs that would sit between 170-180W while occasionally hitting 200C depending upon the program being compiled.  Now, it sits around 200-220W but goes up to 230W often.  The temperatures used to very rarely hit 80C but now hit it quite easily and go above making this quiet workstation fairly loud.

How do I reclaim the previous results?

Hardware:  2023 Workstation parts list 

Operating system:  FreeBSD 14.1-STABLE

Workloads:

• Packages builds using Poudriere (package build system)
• stress-ng (system stress test app):  "stress-ng --timeout 1 --matrix 0 --times --metrics"
• Various VMs
• Games (of course!)

There are many settings, most are not important to the performance (i.e., AURA off).  These are what I am currently using as they are stable (no errors under heavy load).

• Common:
  • XMP I (4800MHz)
  • SVID Behavior [Trained]
  • CPU Load-line Calibration [Level 4]
  • ASUS MultiCore Enhancement [Disabled – Enforce All limits]
  • Performance Preferences [Intel Default Settings]
• BIOS 2301 settings (mainly for safety)
  
  • IA CEP [Enabled]
  • SA CEP [Enabled]
• BIOS 2503 settings
  • IA CEP [Disabled]
  • SA CEP [Disabled]
  • IA AC Load Line [0.20]
  • Unlimited ICCMAX [Disabled]
  • IA VR Voltage Limit [1400]

I typically run stress-ng to get a feel for the settings to see if the temperatures are decent and I have not gone too far with testing.  The real test is when I compile intensive programs.  Compiling a couple of version of OpenJDK simultaneously is very good at causing "CPU 0 COR (1) internal parity error" errors if I have gone too far.  Those are actually better at finding things than running MemTest86.

I cannot go lower with AC LL or use SVID Best-Case Scenario by itself without errors.  I have tried levels 3 and 5 with CPU Load-line Calibration with the above 2503 settings without help.  The levels do not help also when trying to go lower with the IA AC.

Subjectively, it feels like I am fighting the BIOS to lower things and am being ignored for some part(s).  Does 2503 really need to push higher voltages/temperatures to run stable when it was running stable prior to the update?  Has anyone been able to get better results with 2503?  I would prefer not having to go the V/F route as it is a bit intimidating.  😁  I really do hope that there will be a new version of the BIOS that makes it easier to undervolt.

Thank you.

Edit:  Fixed the unit used for Watts (C -> W).  Added actual temperatures too.

[Hari_Seldon]

I went for an unorthodox solution.  While I did not run across others doing this, it seems to work for me.  Under load, the system does not kick the fans up to 100%, does not even reach 80C and gives me approximately the same numbers with the benchmark tool.

I discovered that IA VR Voltage Limit could be used like a power limit (PL1/PL2) to give a better result under stress with quiet fans.  When the SVID offset is lowered from 0.10000 to 0.12000 it actually increased the power draw to the CPU and made the system hotter.  That could be because it brought some value below the IA VR Voltage Limit threshold allowing the CPU to get more power.

1375 was chosen by trial-and-error.  The SVID offset was chosen from earlier experiments.  It could possibly be lowered, but the IA VR Voltage Limit may need to be tweaked along with it.

Hopefully, this has all the relevant changes I made on top of the Intel profile:

ASUS MultiCore Enhancement [Disabled – Enforce All limits]
CPU Load-line Calibration [Level 4:Recommended for OC]
SVID Behavior [Auto]
Maximum CPU Core Temperature [90]
IA CEP [Enabled]
SA CEP [Enabled]
IA VR Voltage Limit [1375]
Global Core SVID Voltage [Adaptive Mode]
- Offset Mode Sign [-]
- Additional Turbo Mode CPU Core Voltage [Auto]
- Offset Voltage [0.14000]

[achugh]

Hi @Hari_Seldon please see https://rog-forum.asus.com/t5/intel-700-600-series/1661-1662-or-1663-bios-update-for-the-prime-z790-... post of mine to get some ideas on what is going on.

Once you get a chance to absorb this information then please ask further questions here.

[Hari_Seldon]

I think I understand what you are saying.  I did not want to continue to lower the CPU Load-line Calibration to undervolt since I was unsure about the consequences of having a higher Vdroop.  I need to verify later, but I think LLC Level 4 may have been my system default under the Intel Profile.  Yes, I did press F5 to reset after installing 2503.

BTW, I just noticed that I did not have revision 0x129 of the microcode even though I installed version 2503 of the BIOS.  See:  https://rog-forum.asus.com/t5/intel-700-600-series/z790-f-microcode-rev-0x129-did-not-apply/m-p/1042...

[achugh · Accepted solution]

I see others have already provided you with great information on this new thread.

Keep in mind that you can always flash the BIOS again. There is no harm in installing the same version. People here have even installed older version of the BIOS when they had issues as that is supported as well to an extent.

In terms of the CPU Load-Line Calibration, it is part of system tuning. Every system is unique and every person has a unique build with their use case. This is why it takes time to fine tune as there are various approaches and method to tuning.

You can start with the system tuning method that you understand and slowly adjust by taking help here. The moderators here are great help once you get started with your system tuning.

[Hari_Seldon]

Thank you for the information.  Just to let everyone know, I confirmed that the CPU Load-Line Calibration on my motherboard defaults to Level 4 (OC) after resetting the BIOS with F5.