A computing 
system capable of parallelizing the operation of multiple 
graphics processing units (GPUs) supported on external 
graphics cards, employing a multi-mode parallel 
graphics rendering subsystem. The computing 
system includes (i) CPU memory space for storing one or more graphics-based applications, (ii) a CPU / GPU fusion-architecture 
chip including one or more CPUs, one or more GPUs, a 
memory controller for controlling the CPU memory space, and an interconnect network, and (iii) an external graphics cards supporting multiple GPUs and being connected to the CPU / GPU fusion-architecture 
chip by way of a data 
communication interface. The computing 
system also includes (iv) an external graphics card supporting multiple GPUs and being connected to the CPU / GPU fusion-architecture 
chip by way of a data 
communication interface, (v) the multi-mode parallel graphics rendering subsystem supporting 
multiple modes of parallel operation, (vi) a plurality of graphic 
processing pipelines (GPPLs) implemented using the GPUs, and (vii) an automatic 
mode control module. During the run-time of the graphics-based application, the automatic 
mode control module automatically controls the mode of parallel operation of the multi-mode parallel graphics rendering subsystem so that the GPUs are driven in a parallelized manner.