Damnation

@Dietmar I am happy too! I'm surprised the solution was so simple, I wish I'd thought of it sooner. It would seem that DSDT tables on the AMD platform are much simpler to those from intel. I guess AMD is not as strict with their ACPI implementation as Intel is.

Until we have a fix for the ACPI0007 ID for XP a simple solution is to add this code into your DSDT table - *This code is for a 16-core 32 Thread CPU. Compile your new DSDT Then simply load this new DSDT with ASL 5.0 asl /loadtable -v dsdt.aml the changes will persist after a reboot.

@Dietmar Yes! I managed to get ASL 5.0 to work! I merged my XP friendly CPUSSDT into my DSDT, compiled it, and loaded with ASL 5.0 ! So, for whatever reason, ASL is fine with loading DSDT+CPUSSDT merged together, but it fails with an A5 BSOD if you try to load them separately. Changes persist on reboot. I have absolutely no idea why this makes a difference, but there you go.

@Dietmar How do I make the .HEX files for patching? or am I misunderstanding?

@Dietmar Thanks. It seems like it's a bit complicated to use, I'm a bit more confident just using grub2 for ACPI patching.

@Dietmar Where can I find this?

@Dietmar Yes I have BIOS 2.2 TPM is on with the default settings, but I made sure to switch it off since since I wanted to install Windows 11 in CSM mode on this machine.

@Dietmar Moving these keys to CurrentControlSet instead of ControlSet001 results in an A5 BSOD

@Dietmar Yes secure boot is disabled.

@Dietmar OK, I checked in the registry and I see that the keys were applied, however XP seems to just be ignoring these keys entirely and my CPU still runs at 140W and DSDT is from BIOS.

@Dietmar No problems thus far, but the DSDT is unmodified, can you make one for the CPU SSDT too? that's where all the changes are made.

@Dietmar Here are the 2 ACPI tables that I load with grub2 for my mod - https://ufile.io/3fv1ijg9

@Dietmar Do you want all of my ACPI tables? or just the CPU SSDT table?

@Dietmar My ACPI tables are for an AMD B550 system though, they won't work for you.

@Sergiaws I think @Outbreaker or @George King should be able to help you automate the XP installation process.

@Dietmar Unfortunately I have not had much luck working with the ASL method, I ended up getting either no change or an A5 BSOD. grub2 seems to still work though, although I noticed that grub2 simply creates a new CPU SSDT table and leaves the original SSDT untouched, weird.

@Dietmar I haven't been able to get this to work thus far, even though asl says it was successful it still loads the unmodded tables. how do I check if test signing is enabled?

Oh that's cool! I might give it a try then. Is asl V5 that hard to use? and if I want to revert to original ACPI tables is that easy?

@Dietmar All I really know is that deprecated Processor() Opcode is no longer in use in these newer ACPI tables that are giving power issues in XP. My mod removes the existing ACPI0007 processor definition and then reintroduces the old Processor() Opcode that XP's acpi.sys expects.

@Dietmar 1.6 watts! Wow! and I thought 44 watts on my 5950x was good. The mod is not that complex, just compare original and modded tables, there isn't all that much of a difference. Now lets hope that @Mov AX, 0xDEAD can code the driver to understand ACPI0007 too.

@Dietmar D'oh! I made a typo in the modded SSDT! new fixed version. https://ufile.io/sj2anz5z

@Dietmar OK, Here is my first attempt at an ACPI mod for you. Load both of the AML files in the MOD folder. The order may or may not be important I'm not sure - i.e if DSDT then SSDT does not work then try the other way around. https://ufile.io/fvbk5kfg

@Dietmar Thanks! I see in dsdt.dat your processors are defined with ACPI0007 ID but curiously no ACPI0010 container. I see ssdt.dat also has some external dependencies to dsdt.dat for processor definitions. Just to confirm, was this board giving you CPU power issues like me? or was it a different board? or were you having a different problem with this board?

@Dietmar Thanks. are you not able to make dumps of your ACPI tables?

@Dietmar Nice! Now we need to find where the Processor definitions are.