If he has that gpu, he most likely has a 60hz monitor. Also, you would be suprised how similar those cpu's are in performance. It definitely is not a "blast the 4770's nutsack out of the water" kind of upgrade. It honestly isn't even worth upgrading from the 4770 to the 2600. I wouldn't even consider upgrading the 4770 on 60hz until you are getting gpu's around the 1080+ level performance. You have to remember a couple of things when comparing these cpu's. 1.) productivity means absolutely nothing for 90% of gamers. 2.)The gaming performance is 10-15% better if you have a good enough gpu. If he bought like a used 1070, rx 580 it would be 5% better MAX. That CPU is probably the very last thing he should even consider upgrading in his system. GPU, monitor, hdd(if he has) to ssd should all be higher priority. If he plays lots of other games, and would be a 4k gamer instead of a 144hz gamer, then getting a rtx 3000 series or rx 6000 gpu would still be a better upgrade then a used rtx 2000 card with a better cpu.