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AMD 6600 on macOS: Zero RPM disabled with softPowerPlayTable (SSDT or config.plist)

AMD PowerPlay technology allows graphics card to vary performance based on demand, switching between performance and power saving. It has automatic operating modes based on predefined parameters It also allows user settings.

Windows 10 and 11 can make a copy of these energy profiles in the PP_PhmSoftPowerPlayTable registry key whose value is so called SoftPowerPlayTable (SPPT), long hexadecimal string. It is a way to have a quick reference by the operating system.

This SPPT key can be read and modified by some utilities. Thanks to this, it is possible to modify parameters of the operation of the graphics card, changing their behavior and/or energy management and port these settings to macOS.

Go here to get info about the XFX RX 6600 XT graphics card on macOS.

Zero RPM

AMD Radeon 5000 and 6000 series cards come from factory with Zero RPM function activated so that fans are stopped below a temperature (60º), this makes them completely silent except when graphics processor is demanded (tests, games, etc.).

On my PC, for example, the base temperature in Windows is 35-40º and in macOS it is 50-55º. Although these are safe temperatures for daily use, some users would prefer to have values similar to those of Windows.

The quickest and most effective way to achieve this is by disabling Zero RPM so that fans are spinning all the time and not just above a predefined temperature. However, this is very easy to do on Windows with the Radeon software but on macOS this option does not exist.

SoftPowerPlayTable

One way to disable Zero RPM on macOS without changing any other parameters is by using the SPPT table created in Windows. To obtain the SPPT table you have to go to Windows, where it is generated as a registry key and exported to a file that we take to macOS where the file is modified and added to an SSDT file or to the OpenCore config.plist file.

PHASE 1 ON WINDOWS

We need 2 apps:

  • GPU-Z (from TechPowerUp): Loads the firmware (vBIOS) of the graphics card and exports it to a ROM file that can be read by MorePowerTool.
  • MorePowerTool (MPT) (from Igor'sLAB): Reads the ROM file with the firmware and manages the PP_PhmSoftPowerPlayTable registry key (delete or create new).

GPU-Z loads the GPU specifications and allows you to export everything to a file with ROM extension.

  • To export (Graphics Card tab) use the arrow icon that comes out of a rectangle below the AMD Radeon logo, to the right of the text box with the BIOS version
  • In the Advanced tab you have to write down the Bus number in the DeviceLocation key, this number (on my system it is 3) is important later, when looking for the SPPT key in the Windows registry.


MPT is where the task of generating the SPPT key with Zero RPM disabled is performed.

  • At the top, choose the GPU model you have installed; it usually shows the bus number (noted above) at the beginning of the name (3 in this case).
  • It is advisable to delete the table that may already exist in the registry from the Delete SPPT button.
  • Load the ROM file generated with GPU-Z (Load button).
  • Modify the Zero RPM option by unchecking the checkbox in 2 tabs: Features and Fan.


There are 2 ways to export the configuration, both ways end up in a text file with the SPPT table:

Method 1: A more complex method is to write the new SPPT table in the registry from the Write SPPT button, this key is located in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4d36e968-e325-11ce-bfc1-08002be10318}\

  • There are some numbered keys here, choose the one that matches the bus number you have written down before: 0003\PP_PhmSoftPowerPlayTable in my system.
  • With key 0003 selected, export it as registry file (REG) or text file (TXT). File structure is different in each case. Both are valid but REG file has a more readable structure.
  • Regedit exports the entire 003 key, not just the PP_PhmSoftPowerPlayTable key.
  • Save the files somewhere accessible from macOS.

Method 2: The simplest method is, from MorePowerTool, click on the Save button:

  • In the Save file dialog choose Save As REG (registry file).
  • A text file with REG extension is generated that contains only the PP_PhmSoftPowerPlayTable key.
  • Save the file somewhere accessible from macOS.

PHASE 2 ON MACOS: softPowerPlayTable in SSDT

Convert the text of the Windows files into a formatted hexadecimal string so that it can be included in SSDT (softPowerPlayTable in SSDT) or in config.plist (softPowerPlayTable in DeviceProperties) and loaded by OpenCore.

This task is possible thanks to Anton Sychev (klich3) and the scripts he has developed to make it very simple.

softPowerPlayTable table from GPU ROM

Extract SPPT table from ROM: Download upp and run it next to the ROM file.

git clone https://github.com/sibradzic/upp.git && cd upp
python3 setup.py build
sudo python3 setup.py install
sudo python3 -m pip install click
upp --pp-file=extracted.pp_table extract -r <rom_file>.rom
  • After running upp, a file called extracted.pp_table is created.
  • In the Scripts folder, simply double click on PPT_script.command.
  • The program will prompt you to drag and drop the file into the Terminal window.
  • Drag and drop the default extracted.pp_table file generated by upp to transform it into a hexadecimal string valid for SSDT.
  • The final text will appear in the Scripts/Result folder. It will have two versions, one in plain text (Results.txt) and the other as DSL (Results.dsl).
  • Copy the content of the selected file and paste into your SSDT.

Note: With this method we have the factory default table. Zero RPM feature has not been changed in any way.

softPowerPlayTable table from Windows registry

This method allows you to bring a modified SPPT table to macOS to disable or modify the Zero RPM feature, customizing the behavior of the graphics card. In the Windows phase we have saved the SPPT table as PP_PhmSoftPowerPlayTable key in the Windows registry and we have taken it to 3 different files:

  • MorePoweTool -> Save -> Save As REG: contains only the PP_PhmSoftPowerPlayTable key
  • MorePowerTool -> Write SPPT -> open Registry Editor -> look for the key in the registry according to the instructions above -> export the entire graphics card section, including but not only PP_PhmSoftPowerPlayTable:
    • Export as REG: Registry 5 file format (preferred)
    • Export as TXT: hierarchical text format.

Either of the 3 files must be transformed into a valid hexadecimal string valid for SSDT. This transformation can be done by PPT_script.command in a very simple way.

  • In the Scripts folder, simply double click on PPT_script.command.
  • The program will prompt you to drag and drop the file into the Terminal window.
  • You can select REG or TXT file to transform it into a hexadecimal string valid for SSDT.
  • Final text will appear in the Scripts/Result folder. It will have two versions, one in plain text (Results.txt) and the other as DSL (Results.dsl).
  • Copy the content of the selected file and paste it into your SSDT.

Note: With this method we have a custom table. Zero RPM feature has been disabled or set up in a value other than default.

Include the hexadecimal string in the SSDT file

This is the code of a fairly common SSDT used with AMD graphics cards (SAMPLE-NAVI.dsl into SSDT folder). You can use it as reference.

DefinitionBlock("", "SSDT", 2, "DRTNIA", "AMDGPU", 0x00001000)
{
     External (_SB_.PCI0, DeviceObj)
     External (_SB_.PCI0.PEG0.PEGP, DeviceObj)

     Scope (\_SB.PCI0.PEG0.PEGP)
     {
         If (_OSI ("Darwin"))
         {
             Method (_DSM, 4, NotSerialized) // _DSM: Device-Specific Method
             {
                 Local0 = Package (0x02)
                 {
// Insert your code here

// End mark

}
                 DTGP (Arg0, Arg1, Arg2, Arg3, RefOf (Local0))
                 Return (Local0)
             }
         }
     }

     Scope (\_SB.PCI0)
     {
         Method (DTGP, 5, NotSerialized)
         {
             If ((Arg0 == ToUUID ("a0b5b7c6-1318-441c-b0c9-fe695eaf949b") /* Unknown UUID */))
             {
                 If ((Arg1 == One))
                 {
                     If ((Arg2 == Zero))
                     {
                         Arg4 = Buffer(One)
                             {
                                  0x03 // .
                             }
                         Return (One)
                     }

                     If ((Arg2 == One))
                     {
                         Return (One)
                     }
                 }
             }

             Arg4 = Buffer(One)
                 {
                      0x00 // .
                 }
             Return (Zero)
         }
     }
}

SPPT table must go right between these comment lines:

// Insert your code here

// End mark

Remember to modify the IOReg path of your graphics card based on your system, it may be different. To know the IOReg path to the graphics card, it can be done with:

  • gfxutil tool.
  • Hackintool: PCIe tab -> Name of your device (e.g. Navi 23 [Radeon RX 6600/6600 XT/6600M]) -> Device Path column -> Context menu -> Copy IOReg path. In my system is: PCI0.PEG0.PEGP.BRG0.GFX0.

For better identification of the SSDT, rename it to SSDT-SPPT.aml and don't forget to compile it to AML format. When you compile the DSL file to AML, the compiler formats text, fills buffer sizes and adds header with comments.

Place SSDT-SPPT.aml in the APCI folder and in config.plist, restart and reload OpenCore.

Check that the SSDT loads correctly

To see if everything is right, run IORegistryExplorer and compare what you see with this image (PP_PhmSoftPowerPlayTable is one of the properties of GFX0 or whatever the graphics device is called on your system):

IORegistryExplorer

If you have added SPPT string with modified Zero RPM, you must see the changes in GPU temperatures and fans spin. In the image there is 3 conditions, graphics made when there is not high demand:

  • Zero RPM off: Zero RPM disabled, temperature does not rise above 35º

  • Zero RPM 45º: fans start at 45º and stop at 40º

  • Zero RPM on: default setting, fans stop below 60º, temps around 50-55º.

    Zero RPM

PHASE 2 ON MACOS: softPowerPlayTable in DeviceProperties

It's another way to get the SPPT table into macOS as a hexadecimal string to the DeviceProperties section of config.plist, with the PCI path that corresponds to your graphics card. My personal experience is that the SSDT method works as is if the SSDT file is well formed but this method usually needs to add the SSDT-BRG0.aml file to work (you have it in the SSDT folder).

Easy method using script

  • Get one of the REG or TXT files generated in Windows.
  • In the Scripts folder is PPT_config-plist.sh
  • Open Terminal and write:
    sh ./PPT_config-plist.sh <REG-file/TXT>
  • The output of this command is a long hexadecimal string that must be saved to be used in the config.plist file.

Manual method

  • Get one of the REG or TXT files generated in Windows.
  • Select the block that begins with “PP_PhmSoftPowerPlayTable”= deleting the rest of the text.
  • Also delete «PP_PhmSoftPowerPlayTable»=hex: leaving only the hexadecimal string made up of several lines.
  • Search and replace:
    • remove the commas
    • remove spaces at the beginning of the lines
    • remove backslashes () at the end of the lines
    • remove line breaks to get a single line string, use Grep in Find and Replace.

Text before the transformation looks like this (the entire string is not shown, just a part):

"PP_PhmSoftPowerPlayTable"=hex:a6,09,12,00,02,22,03,ae,09,00,00,22,43,00,00,83,\
00,18,00,00,00,1c,00,00,00,00,00,00,76,00,00,00,00,00,00,00,00,00,00,00,00, \

After the changes it looks like this:

a6091200022203ae0900002243000008300180000001c0000000000007600000000000000000000000 ...

OpenCore

You must know the PCI path to the graphics card, it can be done with

  • gfxutil tool.
  • Hackintool: PCIe tab -> Name of your device (e.g. Navi 23 [Radeon RX 6600/6600 XT/6600M]) -> Device Path column -> Context menu -> Copy PCI path. In my system is:
    PciRoot(0x0)/Pci(0x1.0x0)/Pci(0x0.0x0)/Pci(0x0.0x0)/Pci(0x0.0x0).

Open the config.plist file in DeviceProperties >> Add > PciRoot(0x0)/Pci(0x1,0x0)/Pci(0x0,0x0)/Pci(0x0,0x0)/Pci(0x0,0x0) and adds PP_PhmSoftPowerPlayTable, its value as Data is the long text string.

DeviceProperties

<key>PciRoot(0x0)/Pci(0x1,0x0)/Pci(0x0,0x0)/Pci(0x0,0x0)/Pci(0x0,0x0)</key>
<dict>
         <key>PP_PhmSoftPowerPlayTable</key>
         <data>Long string, seen as: hexadecimal in PLIST file editors and as Base64 in plain text editors</data>
</dict>

Important: Don't forget to add (ACPI folder and config.plist) the SSDT-BRG0.aml file in which you must check the IOReg path to the graphics card as explained above.

Reboot. If everything goes fine, you will see that fans are spinning all the time with a very low sound, base temperature rarely exceeds 40º (when there is not high graphics load) and test scores have not changed.

Note: slight errors in the hexadecimal string can lead to a black screen when reaching the Desktop, it is highly recommended to have an EFI that works and can boot macOS on a USB device or another disk in case of problems.

April 2023 Note: macOS Ventura 13.4

There are users on macOS Ventura 13.4 who can't disable Zero RPM. Even with it properly loaded from SSDT or from the OpenCore config.plist file (verifiable using IORegistryExplorer), GPU fans are stopped most of the time and temperature ranges between 50 and 55º (approximately 10º more than in Windows), the same as without SPPT string.

There is a way to recover the lost feature. When modifying the vBIOS ROM file in Windows with MorePowerTool, instead of disabling Zero RPM (unchecking option box), it is left checked but the temperatures at which fans start and stop are modified. By default they are configured like this: Stop Temperature 50º and Start Temperature 60º.

I have tried these settings: Start Temperature 40º and Stop temperature 35. With this change, fans spin and stop with the GPU temperature oscillating between 35 and 40º. GeekBench performance is as expected.

Thanks

  • Igor'sLAB whose editor-in-chief is Igor Wallossek.
  • TechPowerUp, GPU-Z developers.
  • Anton Sychev (klich3), SSDT method, PPT_script.command and PPT_config-plist.sh scripts developer. PPT_script.command has its own site as PPT-table-tool.