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ASUS Z390 Load Line Calibration Discussion

joppiano
Level 7
Hi all.

As title says, I would like to discuss the LLC (Load Line Calibration) from ASUS Z390 series.

I have been reading a lot about it recently, and it's quite confusing at times, therefor this thread in hopes of getting even more clarification on the subject.

As of recently, I figured that there was no such thing as "overcompensation" of vdroop due to LLC level. (Source: Buildzoid - video linked below)
Prior to this video, I was under the understanding, that a to high level of LLC (depending of board manufactor) would cause your VCORE to overshoot(vboost) to much. When in reality, there is no such thing, since you would need a negative mOhms resistence, which doesn't exist.

The reason why you're seeing a higher vcore in windows than set in bios, is due to the reading of the Super I/O chip, which is very bad and inaccurate. I think on the MAXIMUS boards, you get the VR VOUT reading, which is way more accurate, but not on the Z390 boards.

On my specific board ASUS ROG STRIX Z390-F, my LLC level goes from 1-7. 1 being more vdroop and 7 being 0 vdroop.
Since my board is using the Super I/O vcore readings, I have been using LLC 5 for my overclocks.

Example 1:
LLC 5
VCORE @ BIOS: 1.360v
VCORE @ P95 SMALL FFTS LOAD(HWinfo): 1.323v

Example 2:
LLC 6
VCORE @ BIOS: 1.360v
VCORE @ P95 SMALL FFTS LOAD(HWinfo): 1.368v

Example 1 shows a vdroop of ~37mv, but I assume that vdroop is actually MORE than 37mv due to the reading inaccuracy.
Example 2 shows that according to HWinfo, I have an overshoot of 6mv during P95 loads. But since the Super I/O readings is wrong, that is not actually my real vcore. It is actually causing a vdroop, but isn't shown in Windows.

Now I am starting to believe that LLC 6 might be the better option, in the goal of reaching for a stable overclock.

Thing is, I had the understanding, that the "perfect LLC level" was causing you to have a "FLAT" transition from idle to load - however, that seems not to be the case after all.
As I understand it, you need a vdroop to counter the over & undershoot which occur in miliseconds upon transition from idle to load and load to idle.
But what is the perfect vdroop then? I guess that all boils down to each individual CPU & motherboard.

Here is a spreadsheet of my OC testing and playing around with LLC etc.

Changes that are made from each test is highlighted with underline.

I know that changing the LLC level, determine how much resistence (in mOhms), which determines how much vdroop you will encounter. But I do not know what each level of LLC represent in mOhms, do you?

I tryid to calculate the mOhms resistence of LLC 5 & 6, but my board doesn't show how many amps is being used, so i tryid calculating this myself.
To find amps used, you can divide watts with voltage, but I do not know if you do "watts / voltage under load" or "watts / voltage set in BIOS".

I am using i7 9700K on a ASUS ROG STRIX Z390-F.

I would like to know your experience with LLC on Z390 boards.
What is your setup, your experience and findings ?
------------------------------------------------------------
Buildzoid LLC Explained: https://www.youtube.com/watch?v=bUaP0r5-xhY

Note: If any of the above information is inaccurate, untrue or such. Please feel free to correct me. Only made this thread in hope to get more clarification on LLC @ Z390 boards.
407 Views
13 REPLIES 13

joppiano wrote:
So when you say "lower LLC" I assume you mean LLC 4 or maybe even LLC 3 - so MORE vdroop and not less, yes?


I just mean at the lower end of the useful section....for ASUS LLC5 at the moment...maybe 6

If you want your CPU to live a long time then lower LLCs for lower or no OCs is, of course the way to go, for 24/7 "sweet spot" OCs i.e. where returns for voltage increases are still linear, then the lower end of the upper LLC settings is best....still some Vdroop and better transient response.

LLC7 and 8 are a horror show for heat and voltage/current...something you'd only use chasing internet bragging rights with no regard for the life of the silicon

It also depends on what you are doing with the CPU....setting up a high clock OC to withstand a bit of a battering with prime at LLC6 only to then never do anything more than game on it will be fine....if you are regularly going to slam AVX instructions then I'd look to setting up a lower OC with less aggressive LLC settings if you want reasonable longevity from the silicon

Falkentyne wrote:
This is a good post.

The "best" LLC depends purely if you are using fixed vcore or adaptive/offset vcore (with c-states) as this affects your idle voltage, so the CPU can downvolt at idle, which it can't do on fixed (it can downclock but not downvolt). With offset or adaptive, you can get by with a much lower LLC than with fixed. Keep in mind the AC Loadline being used has a large impact on offset and adaptive modes. The lower the AC Loadline/DC Loadline value, the more LLC you usually need, so if ACLL is set to 0.01 mOhms, you are going to get nowhere with Level 1 or Level 2 LLC; you may need at least level 4 or 5. With maximum Intel spec AC Loadline/DCLL (1.6 mOhms), you can use level 1 or level 2 LLC, but voltage swings will be very wild based on current.

ACLL isn't important on fixed voltage, and I am not going to discuss DCLL being set different than ACLL because I do not know if DCLL affects vcore on offset mode or not. I know it affects VID, but Intel's spec sheets say DCLL is used to calculate CPU Package Power while ACLL is the CPU voltage supply. I will not discuss this topic.

On fixed voltage, what you want, measured with an *OSCILLOSCOPE*, is the LOWEST PEAK TO PEAK voltage, with the lowest AVERAGE load voltage. That's your goal.

Let's pretend 9900K sample "A" needs a minimum voltage floor of 1.21v @ 5 ghz for heavy AVX and it crashes if it goes below 1.21v, at 5 ghz.
Let's say your heavy AVX draws 193 amps, max intel spec. So there are 3 ways to get that:

1) 1.520v bios set, Level 2 LLC (1.6 mOhms LLC), absolute max safe bios voltage run at Intel spec loadline, this gives 1520mv - (193 * 1.6) = 1212mv load, with 10mv transient dips to 1.202v. Your average load will be 1.212v. Transient spike above 1.520v will be 10mv, so 1.530v. So that's a 330mv peak to peak with god tier transients.

2) 1.380v bios set, Level 5 LLC (0.8 mOhms LLC), that gives load at 193 amps of 1380mv - (193 * 0.8)=1225mv, with 20mv transient dips to 1.205v. And 30mv transient spikes to 1.410v. So that's 200-205mv peak to peak, with 1.225v average load voltage.

3) 1.310v bios set, Level 8 LLC (0 mOhms LLC, no droop). This is 1310 mv - (193 * 0)=1.310v, but transients are TERRIBLE, 100mv dips to 1.210v and 100mv spikes to 1.410v.

All three settings give the same stability at max AVX current.

It's obvious #3 is beyond horrible. The heat and power draw at 1.310v is going to be much higher because the average voltage is higher, and it needs to be higher to compensate for the terrible dips. BTW the power draw will also be much higher than 193 amps if the same prime95 test is done since the load average is higher. I just kept it at 193 to keep it simple.

#2 looks very reasonable. Your bios voltage is not too bad. 1.380v LLC5 is not too bad, and your load voltage drops down quite a bit but the transient below the load voltage is still pretty good. Solid choice. Your peak to peak is 205mv--same as LLC8 but the AVERAGE LOAD VOLTAGE IS MUCH LOWER TO MAINTAIN STABILITY!! Remember what i said--a balance of low peak to peak combined with low average voltage needed.

( NOTE: LLC5 IS NOT 0.8 MOHMS. it's 0.8 mOhms on my Gigabyte board so I'm using my board as an example. I have no idea what it is on Asus. Other tests on overclock.net showed it slightly higher, almost the same as Gigabyte's LLC4).

#1 is terrible. You get the best transients, sure. But you need such a high bios voltage to compensate for the vdroop that your CPU is running at the bare borderline of Intel safe max spec all the time, that could cause the same rate of slow degradation at both idle and load (if temps are kept in check). Because your peak to peak is so freaking high. The peak to peak (>300mv) is not worth the 20mv improvement on a transient. Offset mode with C-states would be much better with LLC1 to avoid a high idle voltage so the voltage drops at idle. Adaptive mode may be even better. (again I can NOT HELP WITH THIS).

But your conclusions are close to correct: on FIXED VOLTAGE, LLC5 tends to be the best. (LLC6 has substantialy more transient ripple).

You need an oscilloscope to find peak to peaks with ripple as the ripple minimums determine your stable voltage floor during heavy loads. VR VOUT only helps find averages.

https://elmorlabs.com/index.php/2019-09-05/vrm-load-line-visualized/


this entire thing has been my saving grace. thank you, mysterious nerd god.

Carlyle2020
Level 10
Thanks to everyone for taking their time and writing everything down with so much detail.
This thread is interesting to read !

I use mostly an air cooler that gets saturated quickly. I tell myself that is the reason why i observe heat generation through LLC levels (and loadline calibration) more pronounced than water cooling folk.

In regards to a 9700k and 9900k in comparion with asus LLC levls i can contribute that for 24/7-use LLC5 did let me overclock the highest.
For me trying to reach 5Ghz LLC6 did produce more heat than it did compensate for in stabiliy (compared to LLC5).
Since the 9700k is running hot already i think you will get further with LLC5 (4?) than LLC6.

Best Regards
Carlyle

ps AC and dc Loadline calibration i set to 0.01 since again this lets me get away with the least heat production for a stable 5Gz OC with a 8700k/8086k/4,9Ghz-9700k/9900ks on air for manual vcore and adaptive.
... auto ac and dc loadline setting is configured for a 9900k at 1,6 ohm IF i recall correctly?!

Arne Saknussemm wrote:
It also depends on what you are doing with the CPU....setting up a high clock OC to withstand a bit of a battering with prime at LLC6 only to then never do anything more than game on it will be fine....if you are regularly going to slam AVX instructions then I'd look to setting up a lower OC with less aggressive LLC settings if you want reasonable longevity from the silicon


Understood, thank you a lot.

Carlyle2020 wrote:
Thanks to everyone for taking their time and writing everything down with so much detail.
This thread is interesting to read !

I use mostly an air cooler that gets saturated quickly. I tell myself that is the reason why i observe heat generation through LLC levels (and loadline calibration) more pronounced than water cooling folk.

In regards to a 9700k and 9900k in comparion with asus LLC levls i can contribute that for 24/7-use LLC5 did let me overclock the highest.
For me trying to reach 5Ghz LLC6 did produce more heat than it did compensate for in stabiliy (compared to LLC5).
Since the 9700k is running hot already i think you will get further with LLC5 (4?) than LLC6.

Best Regards
Carlyle

ps AC and dc Loadline calibration i set to 0.01 since again this lets me get away with the least heat production for a stable 5Gz OC with a 8700k/8086k/4,9Ghz-9700k/9900ks on air for manual vcore and adaptive.
... auto ac and dc loadline setting is configured for a 9900k at 1,6 ohm IF i recall correctly?!


Thanks for your contribution.

You never mentioned your board, Z390 or?

Also isn't manually changing AC/DC Load Line only taken into effect when running adaptive/offset mode? And not with manual vcore.

I tested my system a lot the last few days, and it seems LLC 5 will get me stability quicker than LLC 6 & 7 will.
I don't know if this is true yet, but running LLC 6 & 7 causes my transient responses to be really awful, and causes instability in various stress tests. Because, running LLC 6 & 7 gives me a higher average vcore under load, and yet shows instability, where LLC 5 with lower average vcore doesn't.
Would be nice if someone could confirm if this is true or false.

Also, do you guys reckon it is worth changing VRM Switching Frequency to maybe get better transient respond ?
My specific board (Z390-F) is defaulted at 300KHz and goes to max 500KHz