Unable to use ThrottleStop - any other way to set EPP?

[pantsaregood]

I have an odd issue - my CPU supports SpeedShift, but it doesn't seem like it interacts properly with Windows 11.

Every power plan on Windows 11 results in the CPU being very hesitant to clock itself up. I've confirmed it is related to SpeedShift both by disabling SpeedShift in BIOS and by using ThrottleStop to configure the EPP setting. I've tried a new Windows install to verify that something with the installation wasn't to blame.

If I set SpeedShift to "out of band" mode in BIOS, the CPU clocks up and down very responsively, but the OS can't have any effect on its behavior at that point.

I previously had ThrottleStop configured to run and close on boot to set EPP to a reasonable value. This ended up being a nonstarter because, for whatever reason, ThrottleStop was causing issues with my AVX512 offset - it is currently set to -6, but just running ThrottleStop increases it to the same as my AVX/AVX2 offset (-2), which causes crashing.

Is there any way to modify this directly from Windows? I will say that Windows 11's "Processor Energy Performance Preference Policy" doesn't appear to do anything.

 

[unclewebb]

my CPU

What CPU?

Some recent CPUs have the ability to ignore the Windows and ThrottleStop EPP suggestions. I guess that is what your "out of bounds" BIOS setting is doing.

Exit ThrottleStop, delete the ThrottleStop.INI configuration file and then reboot to reset the CPU.

With Speed Shift enabled in the BIOS, run ThrottleStop and on the main screen, set ThrottleStop to High Performance. This is how to access the traditional Windows High Performance power plan. Now try checking the Speed Shift EPP option on ThrottleStop's main screen and set EPP to 84. In Windows 10, this was the best way to prevent interference between Windows and ThrottleStop when trying to control EPP. I have not used Windows 11 yet so I am not sure if this trick still works.

In the FIVR window, do not check the AVX Offset box and do not check any of the Unlock Adjustable Voltage boxes. Does EPP work? Is AVX512 still being screwed up by just running ThrottleStop? In theory ThrottleStop should not be touching the AVX512 offset register but anything is possible.

Unfortunately I do not have any hardware that supports AVX512 or any documentation from Intel. Without documentation or hardware, I do not think I can solve your problem.

 

[pantsaregood]

What CPU?

Some recent CPUs have the ability to ignore the Windows and ThrottleStop EPP suggestions. I guess that is what your "out of bounds" BIOS setting is doing.

Exit ThrottleStop, delete the ThrottleStop.INI configuration file and then reboot to reset the CPU.

With Speed Shift enabled in the BIOS, run ThrottleStop and on the main screen, set ThrottleStop to High Performance. This is how to access the traditional Windows High Performance power plan. Now try checking the Speed Shift EPP option on ThrottleStop's main screen and set EPP to 84. In Windows 10, this was the best way to prevent interference between Windows and ThrottleStop when trying to control EPP. I have not used Windows 11 yet so I am not sure if this trick still works.

In the FIVR window, do not check the AVX Offset box and do not check any of the Unlock Adjustable Voltage boxes. Does EPP work? Is AVX512 still being screwed up by just running ThrottleStop? In theory ThrottleStop should not be touching the AVX512 offset register but anything is possible.

Unfortunately I do not have any hardware that supports AVX512 or any documentation from Intel. Without documentation or hardware, I do not think I can solve your problem.

My CPU is a Core i7-7820X, so it isn't particularly new. As far as I am aware "out of band" appears to use the same technology that very early implementations of SpeedShift used - Broadwell (I believe) implemented SpeedShift that functioned autonomously from the OS.

It doesn't really look like Windows and ThrottleStop conflict with each other regardless of how I set the power plan - it doesn't look like different Windows power plans actually change the EPP value at all. Changing the power plan in ThrottleStop and then changing the EPP value in ThrottleStop works (as expected), the same way that changing the EPP value without changing the power plan does.

At no point have I checked the "AVX offset" box in the FIVR window. My AVX offset actually isn't being changed, it is specifically the AVX512 offset that changes. My AVX offset is -1 and my AVX512 offset is -6: once ThrottleStop opens, the AVX512 offset gets changed to -1.

I'm not sure Windows 11 handles EPP the same way as previous versions did. There was previously a power setting within power plans that could seemingly control the EPP communicated to the CPU, but that setting in Windows 11 doesn't appear to do anything.

EDIT: If it is something worth tracking down, the behavior is stranger than I thought - the AVX512 offset gets broken specifically when opening FIVR. If I autorun ThrottleStop when Windows boots and then never actually open FIVR to verify the EPP change took effect, the AVX ratio doesn't change.

 

[unclewebb]

Core i7-7820X

I have never owned or used an X-series processor so it is not surprising that ThrottleStop is screwing up the AVX512 offset value. Your processor has been available for almost 6 years. No one ever contacted me to let me know about this bug.

the AVX512 offset gets broken specifically when opening FIVR

Good detective work.

Intel does not publicly document where the AVX512 offset register is hiding within their processors. I have a hunch but the only way I am going to be able to troubleshoot this problem is if you are willing to help do some testing for me. I could add some test code to ThrottleStop so it writes out the contents of the AVX register when it first starts up and then it could write out the contents of the same register when you exit ThrottleStop. I am guessing that the AVX register contains two different offset values in the same register. ThrottleStop might be accidentally zeroing out the AVX512 offset part of that register. It should not be doing that.

Let me know if you want to help and I will send you a test version of ThrottleStop later today. The testing you have done already might help me solve this problem. At least I know what to look for now.

 

[pantsaregood]

Sure, I'd be happy to help. Let me know when you have something available and what data you specifically need collected.

It is, admittedly, a very specific edge-case issue. AVX-512 usually gets thermally limited before stability becomes a concern, so it seems entirely plausible that someone else has experienced this without realizing it. I noticed it because I was tuning an overclock and trying to run AVX-512 promptly crashed a stability test after having recently passed over 12 hours of said test. I ran it again and realized that the reported clock speed was 500 MHz higher than it should have been.

 

[jruser]

@unclewebb did anything ever come of this? Same issue on a 10980XE.

can also help if needed.

 

[unclewebb]

I just sent a TS beta version that should fix this issue.