From the observation it can be concluded that the GPU used for the routine of simple addition presented larger range of number of valid computation than that of CPU. When GPU was configured to maximum block size it presented a 4 times larger range than the CPU. A relationship between block size (number of threads per block) and the capacity of GPU is established and verified. The verification and analysis of relation between index number for this routine and the maximum limit of the CPU to give valid result for is left for future work.