My brother built me a computer in 2014. Since then I have upgraded almost every aspect of it except the CPU. I have a gamerock gtx 1080, NZXT water cooling, samsung SSD, 8 GB ddr4 RAM, but I cannot for the love of god get normal performance in games. A 1080 should run everything amazingly since I have a 1920x1080 144hz display. Can't get more than 110 fps in rainbow six siege or more than 70 fps in the division 2 (both on ultra settings). I think that the problem is my processor not being powerfull enough and bottlenecking. I've got my trusty i5-4670k, it's a very good processor but I see these fps drops in almost every new AAA title with gorgeous graphics. I really want to experience the full 144hz in all my games cause I know I can. My brother disagrees with me, he says that the problem is my PC which makes no sense since I always update it and check for viruses regularly (kaspersky antivirus). My questions are: Should I upgrade my CPU, or could something else be the problem here?