# CPU cache change causes immediate BSOD i9 12900HX



## Slazernomad (Oct 14, 2022)

Hello everyone! Several weeks ago I bought new lenovo legion 7i with i9 12900hx. 
I moved old files with throttlestop 8.7 from my old laptop, removed ini settings and set up undervolting. It was fine with -90 mv for core and cache as always. No issues at all on all profiles with different speed shift (0 for gaming 128 for browsing) 
But then my dumb head decided to download new version of throttlestop. And then it happened. Every time I try to change offset voltage for cpu cache it causes BSOD. It does not even depends on value. On 9.5 version I can see E core cache and P core cache. Tried both - no luck. Then I tried 9.4 version with one cache option - no luck. The. I returned to 8.7 just as I had before but still bsods.. Everytime I reset overcklocking in bios and removing ini file. 
But Everytime I see bsod on core cache changing. I never had this before in many laptops. I change core voltage, save immediately, then cache.
I tried to install xtu but the same happens there! 
The only strange thing is that when I check speed shift and set it to 0 it allows me to do that I want. But if I try to change profile (even if there the same voltages, and speedshift checked (128 for example) I get bsod ago again. So I can't understand the reason what was changed. Windows 11 22h2. Worked today, but stopped working properly with update. Tried all versions till 8.5 that not supported. 
I didn't found anything regarding bsod because of core cache undervoltiing. 
What can I do? Should speed shift be unchecked or checked for this processor? Why it worked before abd sometimes now?
Please help..


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## Count von Schwalbe (Oct 14, 2022)

Looks like a job for @unclewebb 

Slazer, can you post some pictures of the settings that cause it to crash? Also, what error does the BSOD show?

@freeagent move to the throttlestop forum?


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## unclewebb (Oct 14, 2022)

Slazernomad said:


> Worked today, but stopped working properly with update.


If ThrottleStop used to work correctly and now it does not, something must have changed. ThrottleStop is still the same so maybe a Windows 11 update has broken something. 

I do not own a 12th Gen desktop or mobile CPU, I do not have access to any documentation from Intel and I have never used Windows 11. Knowing all that, ThrottleStop might not work correctly on your 12900HX. XTU might be broken too. If they are both broken,  Windows 11 might be the issue.


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## Slazernomad (Oct 14, 2022)

Count von Schwalbe said:


> Looks like a job for @unclewebb
> 
> Slazer, can you post some pictures of the settings that cause it to crash? Also, what error does the BSOD show?
> 
> @freeagent move to the throttlestop forum?


Bsod shows different things. But I found in event viewer errors ROOT\DISPLAY\0000 \Driver\WUDFRd

I do nothing special, just cpu core then apply and then cpu cache which causes a bsod. It worked even today on latest windows updates. Issue happened only when I changed throttlestop verstion. And comeback to old version didn't help ...


*I was able to update bios, chipset, EC and other stuff ... After that I can see that no offset applied. This fair for XTU as well. I'm able to use slider and save but it's not applied. In xtu it just resets to 0 on apply.*


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## unclewebb (Oct 16, 2022)

@Slazernomad

I had a chance to think about your problem. The person that originally tested ThrottleStop 12th Gen support for me had a 12900HK. He had no problem adjusting the cache voltage. I found some screenshots and he was using Microcode Version 0x0E.





Your screenshot above shows that you are using a much newer microcode, 0x1F.

If cache voltage used to work for you and now it causes an instant BSOD, it is possible that Intel has disabled cache voltage control with a microcode update. Intel might have decided to do this to avoid any future Plundervolt issues.

Do you have any older FIVR screenshots handy? Check the FIVR window to see what microcode version your CPU was using.


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## Slazernomad (Oct 16, 2022)

Thanks for replies! I was able to find a solution in specific discord channel. 
The issue was because of cache ratio. For this CPU to make cpu cache undervolting on new bios you should set max cache ratio to 36. I was able to undervolt both e cache and p cache but then I've met bsods on windows restart (on bios load). I found out that decreasing min cache ratio to helps with that. 
So this is my current settings (don't look on clocks)


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