A computing system employing a multi-GPU graphics processing and display subsystem supporting single-GPU non-parallel (i.e. multi-tasking) and multi-GPU parallel application-division modes of graphics processing operations, in order to execute graphic commands and process graphics data (GCAD) render pixel-composited images containing graphics for display on a display device during the run-time of the multiple graphics-based applications, while managing and conserving electrical power and graphics processing resources. An automatic mode control module (AMCM) analyzes the application profiles assigned to graphics applications running on the computing system, and automatically controls the mode of operation of the multi-GPU graphics processing and display subsystem during the run-time of the multiple graphics-based applications.