There isn't a whole lot of room to improve for graphics other than stepping up to a GTX 980 Ti. For the CPU, you'd need a new mobo with the new CPU and you won't get a whole lot more performance without overclocking. Without overclocking, your best bets are still an i7-4790K or i7-6700K due to their high stock frequencies. A GTX 980 Ti will cost over $600 and if you want to upgrade the CPU, that's at least about $400 for an i7-4790K without overclocking with a cheap motherboard. An i7-6700K with motherboard and RAM would be about $550.