Photoshop is a program which uses RAM infront of raw processing power, so working with huge projects stresses more your RAM than your CPU.
Only when you render for instance a gigapixel panorama, then will raw processing power become more vital - for only the time of processing and stitching, that is. After that the project lies within your RAM.
Most games, even new ones, can only be adapted to use single core - for some you can set them to use more but you would have to perform this task every time starting the game as it can only be assigned from Task Manager - which does not have an ability to save the settings.
So yes, spend less money on a processor and use the saved amount on RAM. Your GPU is one of the best performance/price cards on the market out at the moment, so you should be good.