First of all with PCs there is no future proofing. Second the R9 390X is the higher RAM version (8GB instead of 4B) of the R9 290X (which i have and want to sell). The 980 performs better than the 290X and the 980 Ti (recommend Gigabyte) has 6GB but is an absolute beast of a GPU which is close and even beats the boss of all GPUs the Titan X. I would suggest you go with the 980 Ti, its slightly expensive I got mine for Rs. 95000. As far as your power supply goes, 600 is fine but i would recommend at least 750.