https://bugs.freedesktop.org/show_bug.cgi?id=103736
--- Comment #3 from Shiverly shiverly@mt2015.com --- (In reply to Andres Rodriguez from comment #2)
FWIW, Andres Rodriguez reported similar symptoms with a Ryzen system on IRC, and raising voltages / disabling Cool'n'Quiet / disabling C6 states fixed them for him.
I raised the memory and the core voltages specifically. The other voltages like SoC were left untouched.
I didn't have these symptoms in arch or ubuntu 16.04 LTS, only when using this driver/kernel combination (which is only one that keeps both monitors usable). Long compilation jobs don't cause system freezes either.