Different undervolting methods with IA CEP enabled, and how they compare to Lite Load

Vassil_V

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Diving into this hot and controversial topic - undervolting with CEP enabled!
I want to address the elephant in the room first - is disabling CEP potentially dangerous? The short answer is, probably not. I don't really know, and I'm not aware of any evidence that it could be harmful, especially if you have already set sensible settings in your BIOS. This is currently the widespread opinion online, also here in this forum, including with people like citay, who has had lots of experience. Arguing about whether or not CEP is necessary or not is not my goal with this post, I just want to share what I've learned and done.
This is also not intended to be a full guide on how to undervolt, including the basics. Citay's guide is extremely extensive and covers basically everything somebody new to this needs, to get started.

TL; DR - you can check some results and notes here

First a very short backstory, which might provide you with some context.
About a month ago I switched to a desktop PC with a 13700K, from a laptop with a 12900HX, and even before I ordered the components I was already aware of the 13/14 gen issues, so one of my goals from day one was to stick with the basics and follow the official recommendations provided by Intel. Most of them are considered good practice anyway, such as setting ICCMax, proper power limits, enabling C-States and using a power plan in Windows that allows downclocking. IA CEP being enabled is also part of Intel's recommendations, so that's something I made sure is on before I installed Windows, along with applying the rest of the recommended settings, where needed.

My first attempt at undervolting my 13700 was to lower the Lite Load mode as I had read somewhere it does wonders, but I immediately faced a performance hit caused by CEP. Then I read I had to disable CEP in order to properly undervolt using a Lite Load method, but as it was part of Intel's recommendations, I wanted to try a different approach first. With the 12900HX, the only way to undervolt was by using a negative offset as there was no advance BIOS available, so I already had some experience with setting offsets and I just defaulted to this. I tried it with the 13700K and it actually worked great (still does), lowered voltages across the board, temps and power draw noticeably, and there was no performance hit because of CEP.
My Cinebench R23 score with the default motherboard settings is around 29K pts at best, which is enough performance for me, but the problem is the instant thermal throttling at 100C, and hitting the 253W default PL2. Also, voltages spike to 1.46-1.47V during normal usage.
With a -0.125V offset my score went up to 30700 pts, with max power draw 225W and 1.25-1.26V under 225W load. I was happy with this setup so I used it for a few days without issues, then I tried a larger offset to see if it'd be okay. I went with -0.150V which was also perfectly stable, at some point I also set a conservative PL1=125W and PL2=188W and everything was great. Voltages were fine, sometimes spiking to 1.33, but generally under lighter load so no major worries with that. I had tested for stability using y-cruncher, Primer95, OCCT, R23, R24, TimeSpy, and last but not least, through gaming and normal usage, but I watched a Buildzoid video where he mentioned Cinebench R15 is very good at exposing instabilities, so I though I should test with it too. Sure enough, WHEA errors popped up after just 4-5 consecutive runs. I dropped the offset to -0.140V, and it is stable in R15.
Around the same time I started playing The Last of Us Part 1 and for the first time I got a bit concerned by the voltage I was seeing, as I was hitting 1.33-1.34V in-game, and averaging 1.32V, which didn't seem ideal. Just to clarify - it probably isn't a problem, but I wanted to try lower it a bit. So I started experimenting with different ways to lower the max VCore in gaming and also during lighter usage, while keeping CEP enabled. Even though I still have no idea whether it protects my CPU from anything, if I can achieve the results I want with it enabled, I don't see a reason to disable it.

Increasing the voltage offset was obviously not an option, because I had just decreased it from -0.150V to 0.140V. R15 causes me WHEAs when VCore starts hovering just below 1.18V at full load, and -0.150V puts me just in that range. Therefore, I knew what my target voltage under load is - at least 1.18V, but less than 1.19V, so now I needed to find a way to achieve that while maintaining performance, while decreasing the VCore under lighter load and gaming to 1.3V max.

CEP, AC/DC load lines and LLC
If I understand correctly, CEP is triggered by differences between the AC load line (set in mOhms) and the LLC mode (also corresponding to mOhms), where LLC determines how much Vdroop (drop in voltage during heavy CPU load) is being counteracted by the VRM. The AC value lets the CPU know what Vdroop it should expect, so that the CPU can properly calculate the voltage request it should send to the motherboard (at least in theory). If the AC tells the CPU it should expect "x" Vdroop under load, while the LLC allows for "x+5" Vdroop under load, then the CPU effectively gets more undervolted the higher the CPU load is. That's why undervolting by lowering the AC load line is so effective when benchmarking or running heavy loads - it hides from the CPU the fact that Vdroop is expected, so the CPU thinks it's okay with requesting lower voltage as assumes the motherboard will compensate the Vdroop.
If CEP is enabled, this is where it freaks out and starts clock stretching to prevent potential instability, even though the system might otherwise be completely stable and well-performing. This clock stretching effectively reduces the CPU's power and current draw, allowing it to remain stable at a lower voltage, which CEP considers unstable, because it is so much lower than what it expects to receive. So this is why R23 scores can drop by 50% even though you know the Lite Load mode you've selected is stable with your CPU. CEP is not triggered by offsets, because they shift the entire voltage-frequency curve of the CPU, so you can just make it request lower and lower voltages by applying a larger offset, until it is simply unstable. CEP will not kick in as it won't detect a difference between the requested voltage and the supplied one.
However, CEP also seems to have a buffer zone and doesn't kick in unless AC drops to somewhere below ≈67% of the LLC impedance. You can lower the AC load line only, without having a performance hit caused by CEP, just not by much.

The DC load line doesn't directly affect voltage, what it does is to calibrate the power measurement done by the CPU. The DC value in mOhms should match the LLC's impedance in mOhms, so that ideally, when DC and LLC are properly calibrated, VID=voltage supplied to CPU. This ensures proper power measurement, which is especially important if you have a power limit set that's always hit under full load. If DC is set too low, VID will be inaccurately higher, which will lead to inaccurately high power measurement, so you'd effectively power throttle your CPU, on top of the power limits you have set. If DC is set too high, then the VID will be inaccurately lower, which can turn your 200W PL2 into a 205W one, for example. Small differences probably won't be noticeable, but that's the general idea.

So, with all that in mind, what options do we have to undervolt when CEP is enabled, besides just by setting an offset? We have to abide by one general rule - AC should not be set to a value that's below ≈70% of DC=LLC. It sounds simple enough, but it has implications.
If we want to reduce AC to a value similar to a relatively low Lite Load mode, let's say to AC=20=0.2 mOhms (as Lite Load 5 does), DC=LLC cannot be set higher than 20/0,7 = 0.28 mOhms (rounded down). But we have to keep in mind that LLC is applied using presets, so we have a limited number of options for DC, if we want to properly match it to a given LLC mode. Also, going to a lower (as in number, e.g from 8 -> 4) LLC mode (on MSI motherboards, on Asus, e.g., it's the opposite), means that you are requesting from the VRM to compensate more for the Vdroop. To do that, the VRM has to artificially boost the voltage to the CPU when the CPU is under load, but when the load suddenly goes away, this additional voltage applied by the VRM can cause a sudden voltage spike that shoots above the CPU's target VID (called an overshoot), which technically has the potential to be harmful overtime, as it can deliver excess voltage to the CPU. How big the risk is depends a lot on the quality of the motherboard, but it is a risk nonetheless. This exact topic is not something I've researched too much, but the general consensus is that for most people an LLC mode that allows a healthy amount of Vdroop is the better option. I'll appreciate comments on this from people who are using flat LLC or strong modes, what is your experience and setup, and what benefits do you find in this.

Going back to the lowering AC with CEP enabled problem, the above would mean that we have a narrow window to work with for DC=LLC, in my opinion somewhere between 0.4 - 0.7 mOhms. Any lower than that, you'd be asking the VRM for a significant Vdroop compensation. Any higher than that, you can just go with the default DC=110=LLC=Auto, and you don't have to worry about matching DC to LLC, but at the same time you can't lower AC as much as you might want to.

But if you want to worry about matching them... (like me), see below.

With the latest bioses, especially the ones with 0x129 microcode, MSI's motherboards mostly (if not exclusively?) default to the "Intel Default" settings, which have AC=DC=110 (1.1 mOhms) and LLC on Auto. What this should mean is that DC=110=1.1 mOhms is calibrated for LLC=Auto. An important note here is that I've tested LLC=Auto and LLC=8 on my motherboard, and they have the exact same Vdroop behaviour, and other people,with different MSI motherboards, such as the Z790 Tomahawk, have also confirmed the same.
So, this means that with DC=110 (1.1 mOhms) and LLC=Auto=8, VID should match the voltage supplied to the CPU, right?
On mine, and many other MSI motherboards, the only sensor which is available to us for checking the voltage supplied to the CPU is VCore. Unfortunately, it is said to not be completely accurate. According to user SgtMorogan (but not only) on the overclock.net forum, "Vcore will always read somewhat higher than reality due to the impedance between the die and the sensor.". This can be found in this topic, which is widely shared in MSI motherboard-related discussions online. In there, you can find two different tables with supposed impedances, one for Z690 motherboards and one for Z790, with different values in mOhms across the LLC modes. One user with a Z790 Tomahawk board has tested different LLC modes and calculated the supposedly matching DC values. What's interesting is that according to him, LLC=8 pairs with DC=98 (0.98 mOhms), not 110 (1.1 mOhms), as we might assume, given the default settings and the fact that LLC=Auto=8. Additionally, in the same thread, on page 3, user FR4GGL3 has shared the following:

"I asked MSI a few weeks ago. The Questioan was which exact Numbers in mOhms equal to the 1 to 8 Settings of LLC in the Bios.
The answer was:

The “CPU Loadline Calibration Control” settings (Auto, Mode 1 to 8) are fine tune results by RD team’s know-how, so please allow us to keep them secret.

The Auto setting would meet the Intel suggested values.
If user wants less voltage drop (more voltage compensation) when CPU is under high loading, please select Mode 1.
The bigger Mode number the more voltage drop.


So I would say "Auto" is 1.1 mOhms. At least on my Z690 Board. That is also what is listed here on the first few entries"


When I put full load on the CPU using the Intel Default profile with AC=DC=110 and LLC=Auto, VCore always reads higher than VID. I logged data via HWInfo and calculated the average differences across a few short runs of OCCT and R23, by first calculating the difference between VCore and VID for each polling point, and then the average difference, and the result is almost always exactly 0.013V, or 13mV. The runs based on which I've calculated this begin at PL2 and then PL1 kicks in, and I've taken the average of the VCore-VID difference based on all data. But even if I only review the PL2 or PL1 data separately, it is almost always exactly a 0.013V difference, +-2-3mV at most. Setting DC to 98-100 actually causes VID to almost perfectly match VCore. So what does this mean?

Option 1 - assuming that MSI have properly calibrated LLC=Auto to DC=110, being the default, then VCore is indeed inherently inaccurate and always shows higher than it should, about 0.013V higher on average, at least on my motherboard.
Option 2 - if MSI are incorrectly defaulting to DC=110, while LLC=Auto being 0.98-1.0 mOhms, this would more or less explain the lower VID compared to VCore at stock configuration.

I am willing to trust that MSI have not been incorrectly setting DC and LLC by default, as this doesn't even have to do anything with Intel. So, trusting the default settings means that if I want to change LLC to another mode and calibrate DC accordingly, I have to aim for the same 0.013V difference between VCore and VID that I'm seeing with the stock configuration. After some trial and error, I've found out that on my motherboard, LLC=6 paired with DC=68, achieves the same 0.013V average difference as 110/LLC=Auto, under the same conditions.
In order for VID to match Vcore with LLC=6, DC should be set to ≈60, but I've found this impacts performance by a small margin, and I believe it's because it's effectively lowering my PL2 limit.

So, to recap:
- Lowering the AC load line, while keeping LLC=DC=110=1.1 mOhms, is basically what the Lite Load modes do and it's especially effective when high load is put on the CPU. A lot of Vdroop is allowed, but the CPU doesn't know it, so it's not asking for voltage to compensate for it, leading to a significant undervolt during high-load. CEP doesn't like that so it starts slowing down the CPU and reducing the power and current going to it.
- We can undervolt with CEP enabled, it's just more complex and requires a different approach.
- The ground rule is that AC cannot be <70% of DC/LLC; and DC should be calibrated to LLC, so that the VID-Vcore relation is the same as when using the default settings, after measuring it with the most precise sensor you have available.
- Alternatively, you could just go with VID=VCore, as even if this leads to higher inaccurate power reading, you could simply bump up your power limits by a few watts and nobody has to know about it. :biggthumbsup:
- We could technically go as low as we want with AC, as long as we don't break the above rule, but this naturally means that LLC also has to be made stronger (compensate more). Going too low with AC will quickly require an almost flat LLC, which is generally not recommended for most people unless you really know how to set it up and have a good high-end motherboard. It also has other implications too, but I won't go into details.

If we don't want to set a very strong LLC, we have to keep AC at 30-35 the lowest, so that we can set DC=LLC to at least 40. I have not experimented with this range, but went for 1-2 steps above, aiming for LLC=6. It still allows for healthy Vdroop and doesn't have too much compensation. As mentioned above, it seems to match with DC=68, at least as long as I can trust the measurements.

I mentioned that the AC load line undervolt method works the best under high CPU load. This is because even though reducing AC also impacts the VID calculation without load, due to some mysterious way the CPU calculates its VID - using "predicted current", a lowered AC doesn't have the same great undervolting effect when the CPU load is not high enough to induce Vdroop. At least this is how I interpret it. So, what you end up with is higher voltage during light load compared to when you undervolt using an offset, and this can become especially noticeable during gaming. To counteract this, we can combine the two and add a negative offset to a lowered AC load line. This gives us a lower base VID + offset (config 3 below); or slightly lower base VID + surprise Vdroop for the CPU + offset (config 2 below).

I've tested 3 different undervolt configurations, all with CEP enabled, and have compared them with the default Lite Load 5 preset, with CEP disabled. The results illustrate well the benefits of each undervolting method. Here is an Excel file with all the test results, baseline information and some notes.

Config A is with the "Intel Default" lite load profile, with AC=DC=110, LLC on Auto and adaptive+negative offset set to -0.140V. This is my OG setup which I still like due to its simplicity and generally good results. Its only problem is the 1.33-1.34V spikes that can happen during gaming (in specific games).
Config B is a slightly modified version of config A, exploting CEP's buffer zone. Here, AC=80, DC=110 and LLC=Auto. Because AC is reduced from 110 to 80, I've also reduced the offset a bit to -0.125V, and this gives me almost the same VCore under load, but max VCore is lower due to the lower AC, which doesn't cause the CPU to calculate as high VID requests anymore. No impact in performance compared to config 1.
Config C is an experimental one where AC=DC=68=LLC6 (set based on the described above) and again an -0.125V offset. Here we have less VDroop, but also AC is set lower, so the same offset of -0.125V puts me at more or less the same VCore under load as config A and B. However, during light load this gives me even lower max VCore spikes. No impact in performance compared to configs A or B.
Config D is just Lite Load 5 with CEP disabled, so AC=20/DC=110 and LLC=Auto. This gives me higher max VCore spikes than config B and C, but generally performs slightly better at full 188W load. You will see in the file that in Cinebench R23 LL5 achieves on average around 100-150 pts higher result compared to the other setups, but this is not a significant difference. The most potential it has is in an OCCT-like workload, where LL5 could draw noticeably less power, but this seems to be dependent on the specific type of load. I should also note that this is the lowest perfectly stable Lite Load mode for my CPU, as with LL3 CB R24 crashes soon after I start it, and I don't think LL4 will be stable in R15, as the Vcore with it drops to the low 1.170s.

Cinebench R23
This is an interesting one because all four configurations perform similar to each other, but with clear differences based on the power limit.
- At 188W, config D (LL5) has higher average effective clocks compared to the rest, by about 50MHz for the P and E cores, therefore scores a bit higher.
- At 125W, the situation changes and configs A-C perform better, with higher average effective clocks. This sets a trend - the lower the load is, the better the offset configurations perform compared to the Lite Load one.
- The short run R23 scores were very close to each other, with configs A-C being around 30200 pts, and LL5 around 30300 pts.

OCCT Stability test
Here the Lite Load 5 setup is a clear winner at PL2, and it seems that in a heavy load of the type OCCT generates, AC<DC configurations excel due to the large unpredicted VDroop. Because of the low AC value, the CPU doesn't expect much Vdroop, but the OCCT load seems to cause a lot of it, so the bigger the difference between AC and DC/LLC is, the lower the VCore will be.
One thing to note is that the E cores didn't go past 4.1GHz with LL5, while they got up to 4.2GHz using the other three configurations.
Also, I don't understand the mechanism behind it, but the LL5 configuration had a significantly lower power draw at PL2 - 13W less than the runner up, config B.

Config B, where AC<DC=LLC is at second place at PL2, so it seems the AC load line undervolting is definitely the way to go if your use cases generate CPU loads similar to the ones OCCT does.

At PL1, they all effectively perform the same.

Geekbench 6
I tested this because it's a very light load for the most part, but with sharp load spikes here and there, so I thought it'd be a good test of max spikes in Vcore, current and power draw.
Here we also see that the two configurations with DC/LLC=110 + an offset see much lower max power draw spikes compared to the LL5 preset and the DC=LLC=68 + offset modes. LL5 has the highest average VCore, while the VCore spikes are within 10mV range across the four configurations.
Scores were within margin of error, around 2990 pts for single core and 19680 pts for multi core.
The win goes to config B for having the lowest metrics across the board.

Assassin's Creed Odyssey
In this game, Lite Load 5 has by far the highest average Vcore. This resembles the higher average Vcore during Geekbench 6, and is maybe related to the lower average current and/or power draw in these two scenarios. This is also typical during general usage without heavy load. LL5 always maintains the highest average VCore, because there is no offset applied to the V/F curve, and the low AC load line doesn't lead to much of an undervolt during low-load scenarios, when no VDroop is happening.
The win goes to B or C because of the lowest average VCore.

The Last of Us Part 1
In The Last of Us, this time config A, the 110/110 + offset configuration, had the highest average Vcore. Config D/Lite Load 5 still has the second highest average Vcore, and perhaps this game's CPU load is a middle ground where the VDroop is high enough for config D to have lower average Vcore than config A, but not high enough so that the lack of a V/F offset is compensated enough to match config B and D.
The win goes to B or C because of the lowest average VCore.


Conclusions:
Can we undervolt with CEP enabled - definitely! It is certainly more complicated and finicky compared to simply reducing AC and disabling CEP, as there are now multiple parameters to account for - AC, DC, LLC, and offset. But the results can be very good, performance is almost identical compared to Lite Load 5, and the voltage is lower in gaming and light usage.
In Cinebench R23, LL5/config D technically performs the best, no doubt about it, but the performance difference is so negligible it can never be felt. However, LL5 had a significant advantage in the OCCT stability test. Lower VCore, lower power draw, lower temperature, it was a clear winner there. This brings me to a conclusion I never though might be the case - perhaps, there is no best undervolt method (even complexity aside). Some will give you lower voltage in gaming and light usage, others will excel in specific workloads that tax the CPU a certain way. At least this is how I interpret my results, which I admit, are not based on an extensive suite of benchmarks and tests. I could go back and do additional tests with the same configurations, probably first on my list would be a 10-minute R23 run and a 10 minute R24 run with each, but this would take me a lot of time.
Anyway, another thing I think is visible is that basically all four configurations are very capable, and I'm quite happy with the results overall. Cofigurations B and C are the most interesting to me because they combine a reduced AC load line with an offset, and mix the best of both worlds. I think they're great for most people, as they provide good performance and temperatures, and lower the overall max VCore. But the very big difference between AC and DC/LLC that's present with LLC5 seems to be the best choice for optimizing power draw and temperatures, for anybody whose use case is heavy CPU loads such as OCCT, which create heavy Vdroop scenarios. For some reason the same doesn't apply to R23, so if somebody has an idea what's causing this different behaviour, please share.

Hope you enjoyed the read!
 
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Thanks, this is a lot of detail and great testing! (-- though it does incidentally confirm that CPU Lite Mode with CEP off is the simplest undervolting method ....).

what you end up with is higher voltage during light load compared to when you undervolt using an offset, and this can become especially noticeable during gaming.
Does this mean that one would expect it to be easier to get stability (at the same amount of high-load undervolt) when using the CPU Lite Load (CEP disable) method? (--since the voltage drop at light-load isn't as large with this method.) I think you suggested that.

A few questions on this:
Config D is just Lite Load 5 with CEP disabled, so AC=20/DC=110 and LLC=Auto
Lowering the AC load line, while keeping LLC=DC=110=1.1 mOhms, is basically what the Lite Load modes do
I take it that on different MSI boards, the same CPU Lite Load mode can correspond to different AC/DC Loadlines? On my z790 carbon wifi, I use CPU Lite Load Mode 5, and that results in 0.25/0.80: an AC Loadline of 0.25 mOhm and DC loadline of 0.80 mOhm (--i..e., not 0.20/1.10). Also, I suppose that means (on my board) that DC_LL <> LLC (as I assume the default LLC is always 1.10mOhm). But why doesn't MSI automatically set LLC equal to the DC_LL of the CPU Lite Load mode selected (i.e., 0.80 in CPU Lite Load 5, instead of the 1.10 I assume it has)? Or I may have misunderstood something simple here. (It's too bad one can't read the actual value of LLC directly.)

Vcore reads as 0.013V higher on average (than its true value) on your board, but I assume that would vary by motherboard model? Would the table of LLC values also vary by MSI motherboard model?
 
But why doesn't MSI automatically set LLC equal to the DC_LL of the CPU Lite Load mode selected (i.e., 0.80 in CPU Lite Load 5, instead of the 1.10 I assume it has)? Or I may have misunderstood something simple here. (It's too bad one can't read the actual value of LLC directly.)
A lot of us complain about that. To no avail.
Would the table of LLC values also vary by MSI motherboard model?
I believe I read an MSI response to a user that implied this could indeed be the case. And of course, as you already noted, the CPU Lite Load relationship to AC/DC_LL can vary between motherboard and even BIOS version. I believe that relationship might also be modified by whether CEP is enabled and maybe even Intel Defaults Mode vs. MSI Defaults mode. [Although, maybe Vassil_V or others might be able to speak with more accuracy on that last point.]
 
Vassil_V, I think when it comes to handing out prizes for the longest post, you definitely get the Gold medal, sir! I mean, this reads like a plot from a Hollywood action movie script! I‘m sure it was a wild ride.
:beerchug:
I guess it might be time for this old cowboy to hang up his spurs.
 
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What would you advice to test first?

AC/DC 80/110 LLC 8
AC/DC 70/100 LLC 8
AC/DC 50/70 LLC 7
And then manually undervolt until unstable, then raise the voltage again?

I have not really noticed any performance differences with any of the methods, vcore stays about the same, VID is lower with the last settings, but the same as LL Mode 8 with IA CEP disabled.

I'd like to keep CEP on, but maybe its really just an extra safeguard from Intel to avoid crashing when the CPU becomes unstable due to degradation (it needs more voltage to be stable, IA CEP kicks in). I have yet to see anyone tell me that it does something actually important.
Lite Load Auto is recommended too while we all know that Mode 16 (auto default) is way too high, not everything is gospel of course

Also: my CPU crashed horribly with -0.120, and caused my memory retiming to fail during boot. It scared the living [***CENSORED***] out of me, so I might just leave it at LL8 and CEP disabled... 1.36 vcore at low load, 1.010 during high load, i9 14900k
 
Very interesting read. Thanks for this!
Thanks, this is a lot of detail and great testing! (-- though it does incidentally confirm that CPU Lite Mode with CEP off is the simplest undervolting method ....).
That's what came to my mind almost immediately.
But why doesn't MSI automatically set LLC equal to the DC_LL of the CPU Lite Load mode selected
That would be the best solution for everyone who wants a simple undervolting method, which, given the current situation, applies to almost every 13th and 14th gen Intel CPU user.
Is there a possibility to notify MSI about such a proposal? If yes, then you guys with all your tech understanding should write it up and post it to MSI!
 
Studying the Excel sheet a bit, it seems that configuration B might be something to try next to just using Lite Load if IA CEP is to be kept on.
Not too complex in setting up while still providing a well-rounded behavior.
 
Great write-up of extensive and excellent testing, kudos !
But I have to ask again, how can some poor user who is not at all expeienced in dealing with all this complexity, be expected to make head or tails of this mess ? Intel has provided no additional information, just "update your BIOS".
 
Great write-up of extensive and excellent testing, kudos !
But I have to ask again, how can some poor user who is not at all expeienced in dealing with all this complexity, be expected to make head or tails of this mess ? Intel has provided no additional information, just "update your BIOS".
Completely agree: still, LiteLoad modes are there, but even then you’d need to possess the curiosity to go looking on MB specific boards to find Citay’s guide, or one like it.

It’s an absolute shitshow and I will not be buying intel again because of it. With the 7800x3D, for stance, you chuck it in, slap an air cooler on it, and it just works. WTF are intel playing at?

All of that said, I am very grateful for Vass and Citay’s guides. I’m looking forward to imposing Vass config B tomorrow and testing. I will say that a 0.125v offset is probably too aggressive. Going to start with 0.75 or 0.5 and increase from there. I just want reduced temps and VCORE with stability. I’m not looking to min-max everything to the nth degree.
 
Great write-up of extensive and excellent testing, kudos !
But I have to ask again, how can some poor user who is not at all expeienced in dealing with all this complexity, be expected to make head or tails of this mess ? Intel has provided no additional information, just "update your BIOS".
Big problem indeed. I myself had to learn more about these technical details than I would otherwise care, and while this stuff is interesting in its own way, I don't have the time nor indulgence to deal with system intricacies at this level.
I've been an Intel customer since 8088 times. When building my Intel based PCs, I used to just pop in the CPU, set BIOS to defaults and maybe one or two more settings to my liking, and things were good to go, good performance and stability.
Having to start research projects on how to run Intel CPUs with good performance outside of a danger zone is a major fustercluck.
 
One question Vass. I noticed you set PLs at 125 and 188w respectively. Does the 125w not hamper perf?

I’ve been using 175w for both, but not sure if I should also experiment with the lower values? I have seen CP2077 hitting 160w before, but not sure if it’d still work with lower wattage? Cheers :)
 
I will say that a 0.125v offset is probably too aggressive. Going to start with 0.75 or 0.5 and increase from there. I just want reduced temps and VCORE with stability. I’m not looking to min-max everything to the nth degree.
This. I had method A going with -0.120V, but at -0.130V I got WHEA errors in R15, so -0.125 with reduced AC is probably going to cause issues.
 
I meanwhile tested config B with a -0.110V offset.
Seems to work fine here, I see max vcore at 1.275 (spikes included), package temp in R24 (which gives me the highest package temps) is generally in the mid to high 80's with occasional spikes up to 93°C, which I consider acceptable in the face of an uncomfortable 28°C ambient temperature.
R15 is stable.
I'll see if I can push the offset down to -0.115V, and if that proves to be stable, I'll call it a day and go with this setup until I find something breaks.
 
Personally, I use Adaptive + Offset, but also enter a voltage.

This appears to prevent voltage spikes over my set VCore.
 
Great write-up of extensive and excellent testing, kudos !
But I have to ask again, how can some poor user who is not at all expeienced in dealing with all this complexity, be expected to make head or tails of this mess ? Intel has provided no additional information, just "update your BIOS".
You think it’s bad now, just wait. This is what Intel envisions for the next generation…
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Thanks, this is a lot of detail and great testing! (-- though it does incidentally confirm that CPU Lite Mode with CEP off is the simplest undervolting method ....).


Does this mean that one would expect it to be easier to get stability (at the same amount of high-load undervolt) when using the CPU Lite Load (CEP disable) method? (--since the voltage drop at light-load isn't as large with this method.) I think you suggested that.

A few questions on this:


I take it that on different MSI boards, the same CPU Lite Load mode can correspond to different AC/DC Loadlines? On my z790 carbon wifi, I use CPU Lite Load Mode 5, and that results in 0.25/0.80: an AC Loadline of 0.25 mOhm and DC loadline of 0.80 mOhm (--i..e., not 0.20/1.10). Also, I suppose that means (on my board) that DC_LL <> LLC (as I assume the default LLC is always 1.10mOhm). But why doesn't MSI automatically set LLC equal to the DC_LL of the CPU Lite Load mode selected (i.e., 0.80 in CPU Lite Load 5, instead of the 1.10 I assume it has)? Or I may have misunderstood something simple here. (It's too bad one can't read the actual value of LLC directly.)

Vcore reads as 0.013V higher on average (than its true value) on your board, but I assume that would vary by motherboard model? Would the table of LLC values also vary by MSI motherboard model?
Lite Load + CEP off is definitely the easiest way to achieve good results, no doubt about that. I'd argue config B is also similarly easy, as every CPU should be stable with AC=80/DC=110, LLC can be left on Auto, and then it's only a matter of finding the biggest stable offset. And yes, if you tend to see instability under light loads, the Lite Load modes are a better fit because their undervolting effects is not as pronounced under lighter loads. This is also what I don't like about them, as it leads to higher max voltage in lighter usage and higher average voltage when gaming.

It is highly possible that Lite Load modes vary across motherboards, CPUs, BIOSes, and their AC/DC values are also affected by whether CEP is turned on or not. This is why I tried to speak mainly in terms of AC/DC load lines, their relation with LLC and how different configurations affect voltages.

Why MSI don't automatically set LLC=DC, I don't know but it'd be a nice addition. Asus have a "Sync ACDC Loadline with VRM Loadline" feature, for example.
The difference (if any) between the most accurate sensor on every motherboard, reporting the supplied voltage to the CPU, and the VID, will almost definitely vary across boards, but the general consensus seems that Vcore is always inherently inaccurate, overreporting the voltage. For me it's by 0.013V (assuming MSI's defaults are correctly calibrated), for others it might be sligthly different. If somebody has a VOUT sensor, I'd be interested to hear how it matches with VID when using their board's default DC=LLC configuration.
What would you advice to test first?

AC/DC 80/110 LLC 8
AC/DC 70/100 LLC 8
AC/DC 50/70 LLC 7
And then manually undervolt until unstable, then raise the voltage again?

I have not really noticed any performance differences with any of the methods, vcore stays about the same, VID is lower with the last settings, but the same as LL Mode 8 with IA CEP disabled.

I'd like to keep CEP on, but maybe its really just an extra safeguard from Intel to avoid crashing when the CPU becomes unstable due to degradation (it needs more voltage to be stable, IA CEP kicks in). I have yet to see anyone tell me that it does something actually important.
Lite Load Auto is recommended too while we all know that Mode 16 (auto default) is way too high, not everything is gospel of course

Also: my CPU crashed horribly with -0.120, and caused my memory retiming to fail during boot. It scared the living [***CENSORED***] out of me, so I might just leave it at LL8 and CEP disabled... 1.36 vcore at low load, 1.010 during high load, i9 14900k
I'd advise first to test the default DC=LLC=Auto configuration and see what difference you see on average between VCore and VID, if any. This is to have a baseline of what to aim for, as if you manually change DC from the default and don't adjust it and LLC to match properly, your power limits (if you have set any) might not be working exactly as you'd expect them too.
The bigger the difference between AC and DC is (e.g. a low Lite Load mode), the more undervolt benefit you'll get in high CPU load scenarios, at the expense of a higher average voltage during lighter load and gaming. If your CPU is unstable with a -0.120 offset, your best shot of undervolting with CEP enabled would probably be something like config B, but with a lower offset than mine. You'd need to find the sweet spot where AC is lower than DC, so that you get an undervolting effect in high Vdroop scenarios, but also get some benefit in reducing light load voltage because of the offset reducing voltages even without high CPU load.

Studying the Excel sheet a bit, it seems that configuration B might be something to try next to just using Lite Load if IA CEP is to be kept on.
Not too complex in setting up while still providing a well-rounded behavior.
That's what I think too, configuration B seems like the easiest and most well-rounded way to undervolt if you want to keep CEP enabeld.

One question Vass. I noticed you set PLs at 125 and 188w respectively. Does the 125w not hamper perf?

I’ve been using 175w for both, but not sure if I should also experiment with the lower values? I have seen CP2077 hitting 160w before, but not sure if it’d still work with lower wattage? Cheers :)
It does, but not as much as you might expect. Those CPUs are very efficient at around 125W, citay had linked a post somewhere with graphs that illustrated this. In my testing, the difference in performance between 125W and 188W is somwhere around 8-9%, but the sustained package temp is ≈20C lower. That's a very fair compromise in my opinion. If you've seen CP2077 hitting 160W, by limiting PL1 to 125W you'd probably lose no more than 3-4 frames from your max FPS, but you'll certainly have better temperatures. I wouldn't reduce PL2 further though, it's nice to have more power for short bursts.

@Vassil_V,

Perhaps I missed it, but what VCore setting are you using? e.g. Adaptive, Offset, Override...
CPU Voltage is on Auto, while CPU Voltage mode is set to Adaptive + Offset (for configs A-C).

This. I had method A going with -0.120V, but at -0.130V I got WHEA errors in R15, so -0.125 with reduced AC is probably going to cause issues.
If -0.130V was unstable at AC=110, then -0.125V will probably be unstable at AC=80, yes. But there is a very good chance -0.110V will be stable, and this will put you at a very similar voltage under load, but will reduce the voltage during light load, also reducing the spikes. As can be seen in the results, under Cinebench R23 load, -0.140V offset + AC=110 has the same voltage as -0.125V offset + AC=80, but the latter has lower light-load voltage. OCCT changes this - there the difference in voltage between the same configs is 0.03V, but only under 188W load. At 125W PL1 they're the same.

Vassil_V, I think when it comes to handing out prizes for the longest post, you definitely get the Gold medal, sir! I mean, this reads like a plot from a Hollywood action movie script! I‘m sure it was a wild ride.
:beerchug:

I guess it might be time for this old cowboy to hang up his spurs.
I tried really hard to make it as short as possible, that's the best I could do.
:LOL:
 
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