Bug in B660 bios Load Line Calibration

[w4rdog]

This new bug has come up during the search of a way to limit energy cpu demand of my i7 12700 because of another bug explained in this thread

https://rog.asus.com/forum/showthread.php?128548-Bug-in-B660-bios-cpu-voltage-offset

Basically, when all settings are on auto except Power Limit 2 fixed to 180w and CPU Core Current Limit Max to 205 amperes there´s a meaningful drop of performance around 25% in CBR20 when Load Line Calibration is set on 1 instead of 2 and cpu vcore ground under load is constrained to 1.146v.

It doesn´t matter if cpu amperage is on auto the performance loss keeps on but allows loading W11.

Thanks.

[STARRAIN_ROG]

Hi w4rdog,
B660 supports APE function, which can make CPU to operate under the best balance. It is not recommended to adjust the load line calibration to avoid effecting performance.
Thank you.

[w4rdog]

STARRAIN@ROG wrote:
Hi w4rdog,
B660 supports APE function, which can make CPU to operate under the best balance. It is not recommended to adjust the load line calibration to avoid effecting performance.
Thank you.

Hi,

It worked out but even with LLC 1 settled vcore doesn´t decrease under 1.146v and consumption is higher than with -0.05v offset.



Thank you.

Edit: First picture is with APE off and second one is with AC/DC loadline modified.

[trihy]

Until asus resolves this problems, you can try ac dc loadline ohms setting. Cant remember the exact name at this moment, but setting both around 0,05 or so, will cause a lot of vdrop, giving similar results than undervolt. Not perfect, but the only undervolt solution to this boards until asus tell us whats going on.

Just let every other setting at auto.

[w4rdog]

trihy wrote:
Until asus resolves this problems, you can try ac dc loadline ohms setting. Cant remember the exact name at this moment, but setting both around 0,05 or so, will cause a lot of vdrop, giving similar results than undervolt. Not perfect, but the only undervolt solution to this boards until asus tell us whats going on.

Just let every other setting at auto.

Hi,

Thank you for the tip because is a better approach to maximize performance and minimize consumption under load but there´s the same problem with vcore doesn´t go down of 1.146v without a generous drop of output.

This is a good post about CPU AC/DC loadline: https://www.reddit.com/r/intel/comments/ptv38r/observation_on_cpu_acdc_loadline_values_on_an/

So, this is my result with all settings in auto except CPU Current Limit Cache (196A), AC (0.68mOmhs), DC (1.50mOmhs)


Thanks.

Edit: Although a 1.137v appears on picture most of the time running the test vcore is 1.146/1.154v.

[trihy]

I think ac dc undervolt will be useful only for all cores load. Light or one core load will still be at stock values. But at least can lower power and temp when under heavy load.

And you cant go as low as with offset, since we are only using vdrop.

Thats why we need offset undervolt. But is taking forever to be fixed.

Someone said increasing dc loadline will decrease idle cpu voltage. Will have to test this. But its almost impossible to test idle voltage since this boards vcore minimum reports are all bad or wrongs.

[STARRAIN_ROG]

Hi w4rdog,
The first pic is with LLC 1 settled but APE is off, so performance would be better. The second one is with AC loadline modified to 0.68, which is lower than standard voltage, so it would effect performance.
Performance is related to CPU voltage, and modifying load line calibration or AC load line would effect voltage. Also, because each CPU margin is different, you can try adjusting the settings to find a better value to lower CPU voltage but reduce performance loss for your device.
Thank you.