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AC Load Line with High CPU voltage 13900k

Level 9

I recently started messing with Load Line adjustments and got my system stable with LL Level 4 and an AC_LL at 0.45. DC was left on Auto. I assume DC isnt variable and will stay at 0.98 at level 4? 

Anyway, Im seeing high idle voltages in the BIOS around 1.5v and upwards of 1.6v. Running tests in R23 the voltages spike to 1.51v and sit around 1.2v with temps not reaching above 95c under high workload.

Are the high voltages something I need to try and adjust with an offset, or even worry about, and if I apply an offset will that negate the load line setting?


Super Moderator


Depends on what you're trying to achieve. Is the system unstable without these adjustments? If so, what frequency are you targetting and what other parameters have you adjusted before tuning the VRM and AC loadline?

13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090

Im really just trying to get the CPU tuned to the mobo. I suspect I have XMP stability issues but I wanna get the CPU settled before I work on that.

I didn't adjust any other parameters before AC and load line. This is still a new area I'm diving into.

Level 9

LLC4 AC@.45 is pretty toasty for 13900K.  Just an example on my 13900K that I had (nothing special/not binned/average SP), I was overclocked from 5.4 to 5.6 all core, Ecores fixed at 4.3 and was using LLC4 DC=1.02, AC=.16.  Cinebench looping for 10 minutes ran about 82C on custom loop.  There is no way I could run AC@.45. It would hit tjmax immediately running any stress test.  No need for LLC4 if you're just running stock clocks. Use the defaults(LLC3).  If you want to see how LLC4 acts you can leave DC @ Auto.  Start with AC @.30.  Run cinebench as stress test.  Keep lowering AC until crash then add .02-.05 mv to AC for stability.  

I'm running stock clocks right now. Don't really see a need to OC right now. My SP is 96, so nothing special. E-core score is really low, that not helping. I'll give LLC3 a shot and see how it runs.

I initially ran llc4 AC at .30 and R23 wouldn't even start. Had to bump it to run. Ran 10 minutes without issues. Temps never got above 95.

Level 10

What board do you have? I do know that Auto with DC_LL on the Maximus and Strix line of Z690 and Z790's will set the proper impedance (or super close to it), but unsure on boards such as TUF, Prime etc... I believe I have read posts over at that it is still true but I personally can't say 100%.

Let's assume auto for DC_LL is good. XMP could be causing some of your stability issues. So you can either turn it off for now and focus on your undervolt, or make sure that XMP is 100% stable on stock CPU settings and then focus on your undervolt (this is what I prefer so I don't have to keep going back and forth).

If we are going to just leave XMP off for now. First clear your CMOS and start off from scratch. Asus MCE on or off (limits enforced) just don't leave it on Auto/Let Bios decide or whatever it is called. I remove all limits personally but I know I am taking a risk with eventual chip degradation.

LLC 4 or 3 whatever you want to start with. DC_LL on Auto and AC_LL on .20 . Run your stress test, if crashing up your AC_LL, if not lower it. 

You should not be seeing crazy high idle voltages. You sure you didn't mess with e-cores at all?

Voltages have settled around 1.45-1.5 since then, they were high (1.6-1.65) once I rebooted after testing, but I still want to make sure everything is stable. I have the Strix Z790-E. Based on the research I have done this is the impedance table for Asus:

LLC1: 1.75 milliohms
LLC2: 1.46 milliohms
LLC3: 1.1 milliohms
LLC4: 0.98 milliohms
LLC5: 0.73 milliohms
LLC6: 0.49 milliohms
LLC7: 0.24 milliohms
LLC8: 0.01 milliohms

Ill clear CMOS like you suggested to start fresh. I havent touched any E-Core stuff.

What do you suggest for XMP tweaking? Even with XMP off, i've noticed some stability issues. Nothing major and more with specific games.

I've lowered the frequency a bit and messed with some of the timings. Im running Corsair Vengeance 7200mhz. I know its going to be tricky to get it stable. Im ok with running a lower frequency if it means its stable.



So I cleared CMOS and started running LL3 at AC 0.20. PC didnt like that. Ended up swapping to LL4 and was able to run R23 for a full 10 mins at AC 0.47, DC on auto. Maybe I have low quality silicon. Temps hit 96.

From what you're saying and the LLC input values you have to use to run CB have a poor quality chip.  Your stable AC value of .47 on LLC 4 is above average for a 13900K.

LLC 3 Defaults:  DC=1.1  AC=.50

That's unfortunate, but I suspected it.

If I'm not OCing, should I run LLC3 and fine tune it or is LL4 fine?