Computer systems and methods that utilize a GPU whose operation is able to switch between ECC and non-ECC memory operations on demand. The computer system includes a graphics processing unit and a memory controller and local memory that are functionally integrated with the graphics processing unit. The memory controller has at least two operating modes comprising a first memory access mode that uses error checking and correction when accessing the local memory, and a second memory access mode that does not use error checking and correction when accessing the local memory. The memory controller is further operable to switch the operation of the memory controller between the first and second memory access modes without rebooting the computer system.