The Hero of Orlais :
Rexper :
What are your usages for each core of your CPU whilst playing?
got to say, that's somewhat a stupid question, but probably good to ask, gta 5 is a gpu intensive game and ryzen 1600 is will not likely bottleneck a gtx 1080
This isn't a stupid question at all. In fact, it is very probably the CPU is causing this 'low', FPS. As seen in this review, using the same setup, the CPU bottlenecks at an average of 67 FPS with a minimum of 47FPS.
http://www.tomshardware.com/reviews/amd-ryzen-5-1600-cpu,5073-6.html
And 90% of the time when the GPU isn't hitting 100%, it is due to CPU 'bottlenecking'.
Also, this test must be taken for diagnosing the issue anyway.
Also, OP, unless you are aiming for 100hz performance goals, this FPS you are receiving isn't particularly 'low'. Any framerates above your refresh rate wont be distinguishable, really.