Carrizo APU Overclocking/Undervolting

Hey guys,

on my search for a tool that could be used to downclock the AMD APU of my Lenovo Y700 notebook i came across a neat tool called "AmdMsrTweaker" that was initially released in the xtremesystems.org forum and could be used to modify power states of old AMD K10 CPUs.

Some guy took over this project a few years ago and released a new version (1.1) with partial support for Trinity / Richland / Kaveri APUs. Luckily it does work with the new Carrizo APU generation too, so i decided to write a small guide.

First of all, this tool is for command line (Windows) only. That means there is no user interface that will pop up and let you change some settings with a simple mouse click (but it is not really needed actually).

I didnt found a working download link for the tool but the source code is still available so i recompiled it with Visual Studio. You can download it directly from the link at the end of this post. The .zip file contains the AmdMsrTweaker.exe and some files of the WinRing lib which this tool is based on (not sure what it does though).

Note: All attempts using this tool are at your own risk and will void warranty, it could even damage your CPU or other components !

If you execute the tool without any arguments it will output the current power states and some CPU info. On my FX-8800P it looks like this:

As you can see we get all the information we need.. base clock, multiplier, voltage steps.. even the north bridge states. The only bug with Carrizo APUs: The voltage values are wrong and shown lower than they are in reality. But that's no problem as we can work with those values and pretend that they are the real ones. F.e. the max turbo state P0 uses 1.1V but tools like HWInfo showing 1.325 V. Now if we decrease the voltage one step to 1.0875V we get 1.319V in HWInfo.

Now the important part.. how to change the P-states:

You can simply add arguments for execution in the command prompt after the .exe like this:

AmdMsrTweaker.exe P0=34@1.0875V

The syntax is clear, we are setting the P0 state to 1.0875V (1.1 - 0.0125 as mentioned before) and the multiplier remains at 34. This will result in 3.4GHz (34 * 100 MHz base clock) which is the max turbo for this APU. You can even add more arguments if you need:

AmdMsrTweaker.exe P0=34@1.0875V P1=32@0.945V P2=.....

All those changes will remain until you restart you PC (or shut it down if you use fast/secure boot options in BIOS), i.e. every time your BIOS will be initialized those changes will be reverted to the default values. To overcome this i will show you how to run the tool on Windows startup.

Run on startup

Windows 8.1 / 10

First we need a new Windows Batch File. Open Notepad and create an empty text file, got to File -> Save as.. and select All files in the Save as type: box. Name it MsrTweakerStartup.bat or whatever you like.

Now add the command at the first line of your newly created .bat file to start the tool with your custom arguments, here an example:

START C:\YourFullPathToTheFile\AmdMsrTweaker-v1.1\AmdMsrTweaker.exe P0=34@1.0875V P1=32@0.945V

To see if it works you can double click the .bat file, the line above should be executed and you see a command prompt shortly popping up. Now we need to tell Windows that our batch file should be executed on startup. Go to your start menu, choose Run and open shell:startup. This will open the windows startup folder, now create a shortcut of your batch file and move it inside this folder. That's it !

After restarting your PC you will notice that the command prompt is popping up after Windows login, that means your .bat file is executed automatically.

Hope this will help you as much as it did for me and many thanks to the developers of this tool !!!

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Carrizo APU Overclocking/Undervolting