I am running an i5-2500k from 2011 as my desktop. Just dropped an rx580 in as my graphics card, and it's running great for my light gaming purposes (overwatch, 1080x60 screen). I think I could get away using it for 1440 or 1080x120 pretty comfortably.
Will probably do a new system in the spring with my income tax return. Leaning towards R7, maybe Threadripper, currently. They're finally getting faster enough to justify the cost.
aside: switched to hackintosh for my OS last year, been very happy. Hoping the osx-amd support isn't too difficult when I upgrade.