MCE explanations and others

[Shamino]

[Feklar]

This should be sticky'd.

[Arne Saknussemm]

ROG straining the camel right there!

[HiVizMan]

Thank you Shammy

[Shamino]

This also raises the question, is 'stock performance' absolute in today's context? with TVB and XFR on AMD, frequency depending on power and power on temps, tests carried out on an air cooler will differ from tests carried out on custom water, without even bringing in the question of what ambient temp to test at. One can only test with a typical cooler, which seems to be an AIO on these platforms.

[mdzcpa]

This is a great point. Reviewers and users need to be very aware of these technologies in the current CPUs and supporting boards. They add an almost infinite number of possible "stock" or "baseline" performance norms. These variables will need to be dealt with when making comparisons. Reviewers will need to be very detailed if they plan on presenting any results that are "apples to apple."

One thing I DO very much like about TVB implementation on the new Asus boards is the rewards built into power consumption and performance through smart component /cooling selection. Without even overclocking, performance and efficiency can be dynamically gained (or lost) based on cooling choices.

This is a great thread Shamino. It draws attention to the fact that new motherboards need to be reviewed in a entirely new light. Routine comparisons based on the old "tried and true" review methods need to be changed.... and in some cases farily drastically.

I must say that after getting my Hero XI up and running, and having some time to really work with it, it has become clear there is a lot more going on than looking only at VRM design, VRM temps and Vdroop measurements at associated voltages and clock speeds. I've achieved some pretty stellar performance at surprisingly low voltages and its interesting to see those parameters change dynamically by adjusting cooling effectiveness. Asus appears to have done a very nice implementation of MCE (their version of it) and TVB.

This also raises the question, is 'stock performance' absolute in today's context? with TVB and XFR on AMD, frequency depending on power and power on temps, tests carried out on an air cooler will differ from tests carried out on custom water, without even bringing in the question of what ambient temp to test at. One can only test with a typical cooler, which seems to be an AIO on these platforms.

[Luck100]

MCE
If you played with Cache OC, you see that it is very intolerant of any undershoots. Straightaway you would hardlock or BSOD. You can even test it at default. Since it shares the same rail as core, set core ratio to something really low like 40x. Set min and max cache ratio to 43x and set a manual voltage like 1.15v. Run a heavy load like prime 95 non AVX. Dynamically slowly reduce the voltage 5mv at a time. You will find the VMIN this way. Once you find the VMIN under continuous load, stop prime95. If it doesn’t hang, run it again, back and forth between running and stopping. Even try booting straight from bios with that VMIN. You will see that this VMIN requires a guardband for transient load changes, meaning you will need 5mv+++ more. You will observe bigger guardbands needed at higher cache. Obviously the better the transient response, the guardband requirement is smaller.

How do you adjust voltages or other BIOS settings without rebooting? It sounds like you have a tool to click and change it in Windows.

[vvoid]

How do you adjust voltages or other BIOS settings without rebooting? It sounds like you have a tool to click and change it in Windows.

The tool is called Intel XTU, "Intel Extreme Tuning Utility" and can be downloaded from Intel's website.
---

And @Shamino, thanks for this very informative post! The AVX-offset issue is exactly what I have stumbled across and what I couldn't understand. Now it all makes sense and it got me curious, so I did some testing myself. Here are the results.

HW: Z390 Strix-F (SiC639 powerstages, like Hero/Formula/Code), BIOS 0805, i7-9700K
Settings: bclk 101.3, core x51, cache x47, 500KHz VRM Switching Freq, Adaptive Voltage +0.001 offset, Best-Case setting (anything else relevant?)
Measurements: Multimeter across VRM output bulk caps. (Hope that's ok??)
Load: Prime 26.6 Small FFTs, 8 threads, CPU Package 78°C - 84°C max, depending on voltages tested.
Voltages are read under full Prime load, lowest setting where Prime wouldn't complain/crash/bsod/whatever is shown.

LLC5
constant multiplier

BIOS 1.260V, Measured 1.266V, Power 158W (HWInfo)

AVX-1 (XTU), trying to trigger crash

BIOS 1.300V, Measured 1.306V, Power 167W (HWInfo)

--> Guardband 40mV

LLC4
constant multiplier

BIOS 1.300V, Measured 1.268V, Power 163W (HWInfo)

AVX-1 (XTU), trying to trigger crash

BIOS 1.315V, Measured 1.281V, Power 169W (HWInfo)

--> Guardband 13mV (!)


Conclusions:
- The difference between LLC4 and LLC5 is quite significant. Much bigger than a briefly tested LLC5 vs. LLC6.
- LLC5 still overvolts slightly under load, which is not reflected in HWInfo-readings at all. LLC4 and LLC5 both appear to undervolt, but, according to my measurements, this only holds true for LLC4. (LLC6 is actually shown correctly as overvolting.)
- VRM switching frequency does indeed seem to help, at least in my case, and I generally don't understand why Asus keeps sticking to a default of 300KHz on these simpler boards. I've also measured VRM temps (at backside of the board) and the difference is really within margin of error for my measuring equipment, maybe 1-2°C. I see no reason not to just set 500 and forget about it. By the way, these SiC639 powerstages are actually high-speed ones (up to 1.5 MHz) and the datasheet doesn't even mention values as low as 300KHz, starting at 500KHz for their charts...
- I found the best way to trigger a guardband-violation is setting AVX offset 1, then, during Prime load, just repeatedly open Win 10 Startmenu and Settings dialog, just wildly clicking through the different subpages of Settings, especially the Apps page. It's a sure and quick crash/BSOD for the Prime load if voltage is too low. For me, switching multipliers or decreasing boost limits didn't trigger crashes at all.
- Most (all?) of these so-called overclocking tutorials/videos fail to mention this topic at all. They just blindly set an AVX offset, because, you know, everyone knows AVX isn't stable at the same freq/voltages, lol.
- Finally, for overclocks needing AVX-offset I'm going to use LLC4 from now on, without offset probably still LLC5.

Open Questions:
- In what significance is the guardband dependant on the absolute voltage? I mean, would a test at x45 bclk 100 with much lower voltages yield a different result?
- It's a bit strange that my LLC4 AVX-1 setting measures less voltage, yet is using more power according to HWInfo ?
- I've tried testing 2 instances of Prime, 26.6 and 29.6 AVX in parallel, but as soon as AVX threads are present, the offset is suddenly applied to all cores. Why? Is that intended behaviour?? It's strange, because with the Startmenu/Settings test this doesn't happen. You can clearly spot single cores running at -1 in HWInfo, but the other cores keep running the higher multiplier for the Prime load just fine... (?)
- Another way of dealing with this whole affair might be to just forget about AVX-offset and employ appropriate max power limits. You know, to keep AVX loads in check while still maintaining max boost clocks for normal load. Something worth investigating further.
- I'm now very curious how other boards would perform in a test like this. Most interested in the Z390 Gene with its IR3555 powerstages, but also the Gigabyte boards with their doubler-equipped "bigger" VRM. Anyone got some data?
- Back to the Gene, IR3555. Is the body-breaking feature of these powerstages actually implemented? I'd expect this to help in scenarios like these, no?

Thanks for reading, discussion welcome!

[Luck100]

The tool is called Intel XTU, "Intel Extreme Tuning Utility" and can be downloaded from Intel's website.)

I have the Asus version of Intel XTU that comes with the Maximus XI Hero. It doesn't have the ability to change voltages. It can only change multipliers, power limits, and a few other things. But no voltages. I wonder did Asus gimp this version of XTU, or does my motherboard not support voltage control from windows?

I've tried testing 2 instances of Prime, 26.6 and 29.6 AVX in parallel, but as soon as AVX threads are present, the offset is suddenly applied to all cores. Why?

Yes, this is how all the dynamic clocks work. At any given instant in time, all the cores must run at the same multiplier. It can sometimes look otherwise in HWinfo, but that's because it's not actually measuring all the core multipliers at the same instant of time.

Another way of dealing with this whole affair might be to just forget about AVX-offset and employ appropriate max power limits. You know, to keep AVX loads in check while still maintaining max boost clocks for normal load. Something worth investigating further.

This is exactly what I've chosen to do. Keep AVX offset at 0 and set PL1/PL2 to ensure I don't exceed 80C under any sustained or transient load. That means I'll downclock only under extreme loads like P95 with AVX, while games that use AVX don't pull nearly enough power to hit the power limits. This works nicely in combination with offset or adaptive voltage, as you'll also get a VID and Vcore reduction when downclocking (which helps bring you back under the power limit).

[vvoid]

I have the Asus version of Intel XTU that comes with the Maximus XI Hero.

Well, I guess just use Intel's own version then.

Yes, this is how all the dynamic clocks work. At any given instant in time, all the cores must run at the same multiplier. It can sometimes look otherwise in HWinfo, but that's because it's not actually measuring all the core multipliers at the same instant of time.

Ahh ok, thanks, forgot about that.

What exact settings are you running on the Hero to achieve the balance of AVX/non-AVX?