Undervolting 13900KS on Z790 Hero / VF points

[sergio77]

I'm using ROG Maximus Z790 Hero in combo with Intel i9-13900KS, the latest BIOS.

1. Trying to use "Voltage/Frequency points" which are used in the process of overclocking or tuning the performance of a CPU. I have found that the voltage offset from all the VF points except ones for highest multiplier (9-10-11-th) has been ignored. Just 11th point offset is always applied to the max multiplier that I've set.

2. Whatever offset value I've entered in e.g. in 8-th or 6-th point  will be ignored. E.g. I can enter -0.200V for 5-th, 6th, 7th VF point and it will be ignored when P-Cores are under multiplier of x53. It will use the offset from 11-th VF point that is set to -0.030V which is used for multiplier x60.

3. I  have disabled Undervolt Protection in Asus UEFI. Also I have used the rule n+1 should be always higher voltage, BCLK is 100MHz.

This kind OF CPU Voltage tuning is working on my Z490 APEX. 

Is it BIOS bug or something specific to KS model?

e.g.

P-Cores multiplier 

1x62

2x62

3x62

4x60

5x60

6x56

7x55

8x50

Voltage offsets by VF point

1. -0.10

2. -0.08

3. -0.07

4. -0.06

5. -0.05

6. -0.04

7. -0.03

8. -0.02

9. -0.01

10. -0.01

11. -0.01

CPU voltage offset +0.03V will always be applied no matter the active ratio multiplier/frequency? Why?

[INFP · Accepted solution]

Intel's microcode update has made it impossible to undervolt through SVID offsets. You can change microcode from Tweaker's Paradise. Additionally, Undervolt Protection should be disabled. However, the BCLK may not be fixed to 100.

I haven't tried it, but maybe it's possible if you enter a negative value for Actual VRM Core Voltage Offset and a positive value for SVID Offset (If Intel has only blocked Undervolt)