X670e Carbon, Load Line Calibration (LLC) Settings

[lostking20015bf02e6]

Does anyone know the meaning of mode 1-8 below? I am assuming mode 8 is the one with the least overvolting, right?

 

[jfrobinso156502de]

It sure would be nice to have an explanation of these settings. Other MB mfg's provide more info on LLC settings than MSI.

 

[citay]

Load Line Calibration is the classic remedy against Vdroop, i.e. a sudden drop in CPU voltage when the load suddenly increases, and is used especially when you want to overclock (not that most CPUs are any good for proper overclocking anymore, nowadays OC often just ruins their efficiency further). LLC is to prevent the manually set VCore from dropping too much under load, and the overclocked-or-otherwise-tuned CPU becoming unstable from too much voltage undershoot (or negative overshoot, however you wanna call it). LLC can minimize the voltage differences between idle and load. But if overdone, it can lead to an unnecessary high voltage in idle.

The voltage decreasing under load, that is a normal "feature", meaning it is the normal behaviour, not something that should always be fought against. But if you determined that you need to use LLC (for example when it otherwise becomes unstable with whatever your settings are), then it will work against that sudden voltage drop under high load.

Usually the modes are something like this:

The "No OV" is the default curve, that's how the CPU and VRM behave normally. On the X-axis you see the amount of load for the CPU, on the Y-axis you see how VCore behaves. With "No OV", VCore is allowed to suddenly decrease with high CPU load. That is primarily so that when the high CPU load suddenly stops again (as it would), the VRM doesn't keep pumping in lots of juice into the CPU for a split-second and causes the VCore to exceed the specifications. Because the VRM is never as fast as the load changes on the CPU, it always takes a bit of time to adjust to a new load situation, it "oscillates" on any sudden load changes. And when you go back from heavy load to light load, this oscillating VCore - if there was no Vdroop - would make the voltage spike above the specification for the CPU.

This is an illustration from Anandtech about that:

When suddenly going from light to heavy CPU load (which is also called a transient load), there is Vdroop, so that once the heavy CPU load stops, the VCore doesn't spike above spec. In other words, with the "No OV" setting (which should be active when you leave LLC on Auto and haven't touched VCore either), the board will prevent VCore from exceeding spec after transient loads and potentially damaging the CPU over time.

But there can be situations when this Vdroop is not wanted, when you have changed VCore (by whatever means, there's several), and suddenly this Vdroop makes the voltage drop too much under certain load situations. Then you can set LLC to counteract it.

Again looking at the graph from the MSI BIOS, Mode 8 would be minimal LLC, just counteracting Vdroop a little. Then the higher you go, the more it will try to prevent Vdroop. And once you go to Mode 2 or Mode 1, it even overcompensates, meaning now VCore will even shoot up a bit higher with sudden high load, so the normal behaviour is more or less reversed. That would be extreme LLC, there are very few cases where such a behaviour would be needed. Most people will probably stay between Mode 3 and 6, i'd say.

Traditionally on MSI, LLC mode 3 and 4 tend to give the best results (that is, when you determined that you need LLC). Also, it's been said that when using LLC, keep the switching frequency on Auto or quite low (500 KHz for example), because it may have been tuned for that.

Having said all that, modern high-end CPUs like the Ryzen 9 7950X have very limited overclocking potential, even with excellent cooling. It's best to leave them up to their own devices in how they want to boost etc., AMD and Intel are very aggressive there anyway by default, exploiting 99% of the CPU's capabilities. Yes, you could probably eke out another 100 MHz or so for all-core load, which will net you a slighltly higher score (low-single-digits) in a fully multithreaded benchmark, but won't do anything for more realistic real-life load situations. And very quickly the temperatures will limit how much VCore you can add.

 

[dakotah.dekle15bb02e0]

It sure would be nice to have an explanation of these settings. Other MB mfg's provide more info on LLC settings than MSI.

Asus and Gigaybte show it graphically with a moving curve which corresponds to which setting.
Gigabyte also shows in plain text what the standard is.
With MSI you have to guess if you don't have an oscilloscope because the overloads are so short that you can't really record them even with Windows software. To make matters worse, the clown club uses a different number of steps for the CPU and the chipset.
Buildzoid has some nice measurements on Youtube and also shows how broken the settings are on some MSI boards. MSI does not even stick to its scheme consistently, the golden center is not always standard. In the same way, almost every setting at MSI ensures that the standard voltage is also increased. LLC naturally raises the voltage, but it should not permanently exceed the standard VIDs, even with the most extreme LLC, the max VID should and must be maintained.
The PWM frequency, which can be set from x-1000kHz, also fits the theme ... So what is standard? When is what set automatically? Also a big secret at MSI. Here too, Buildzoid once measured an MSI board with an oscilloscope and discovered some shocking results.
If MSI does not display any default values, you can usually assume that the function is broken and does not do what it should. So much as a spoiler, above 750kHz MSI is so broken.