Power Management Mode: This setting makes use of a modern GPU's abilities to support different performance levels depending on how much power is required. Normally, the graphics card will monitor GPU load, and when under minimal load, will lower its clock speeds (downclock) to what is known as 2D or Idle clock speeds - the lowest possible speed - in order to save power and reduce temperatures. This occurs when using the Windows Desktop for example. This setting does not alter that behavior, instead it controls what happens when the GPU is operating at what is known as 3D clock speeds, which are activated when running games and other 3D applications.

The available options are Adaptive and Prefer Maximum Performance. If Adaptive is chosen, the graphics card automatically steps down in clock speed in games and 3D applications if they aren't generating a high GPU load. If Prefer Maximum Performance is chosen, when running any game or 3D application, the GPU will maintain its maximum clock speed regardless of load. The Adaptive setting shouldn't cause any problems in modern games, as the GPU will always run at full speed when required without interruption. However, in old games which generate much lower GPU loads, the graphics card may constantly downclock when set to Adaptive, and this may cause issues such as fluctuating performance and stuttering. Alternatively, using the Prefer Maximum Performance option should also be fine, as most games require maximum clock speeds for optimal performance, but you may run into situations where the GPU does not properly downclock back to 2D clock speeds once the game is exited.

I recommend that Power Management Mode be set to Adaptive under Global Settings. For any games for which you believe your GPU is constantly downclocking, you can change this setting to Prefer Maximum Performance under the Program Settings tab to ensure the highest possible clock rates at all times. Remember that this setting only relates to games and other 3D applications, not to 2D applications or the Windows Desktop. Note also that if you run a multi-monitor and/or high refresh rate display your idle clocks may be slightly higher regardless of this setting, which is normal.