Use msi afterburner and rivatuner, put osd and look at the percentages if your 1070 is running at 50% and your cpu is at 95% well you do have a bottleneck, but if its the other way around, its really graphically intensive game your 1070 is at 99% and your cpu is at 35%, for instance, well you are good to go. it always depends on the game your playing and what your aiming for in terms of frames per second and graphical quality. For hardware there not many choices for the price range your giving, you could look up on eBay for a I5-3570K or an I7-3770k. hopefully, you have a Z68/Z77 motherboard then you should be able to get a decent overclock and alleviate the bottleneck a little.