Hi, I have the same problem, recently update my pc and start using 2 monitor (VGA)
PC
CPU: AMD Ryzen 3 3200g + vega 8
RAM: 12gb ram (4gb @ 2666 + 8gb @ 2666)
MotherBoard: GA A320-s2h v2
Game Mode:ON
Since i add more ram and use the second monitor, my codex start overload, for no reasson, since when i have 1 monitor and 8gb ram (2x4gb @ 2666) i could stream League of Legends at high settings normally, at 720p 30fps (OBS Settings) , but now i can't since start getting lag on OBS and the warnig of Codex Overload , I change the setting to use CPU instead of GPU to stream and that makes a little bit of less lag, but still, maybe it could be the other monitor that I add to my pc ?
I use 2 vga monitor, using an adaptor a the regular VGA input