After an extended experiment, including reinstalling Windows 10, I have finally found what I believe to be the smoothest setting possible for RX 480 for GTA V.
It is done with almost 30 times of in and out of the game, tweaking a lot of different settings.
My hardware spec:
CPU: Intel i5-6600
RAM: DDR4 3000 C14 64 GB
Storage: SSD w/ system also installed
GPU: Reference RX 480 water cooled, MSI Gaming X RX 480, both clocked to 1265 MHz (reference's boost clock)
It begins with the fact that I am experiencing a lot of stutter, be it micro or more significant, they are all over the places and wasn't what I expected from RX 480 CF.
Having seen how good a 980Ti can run the game, I believe if that wasn't AMD's hardware limitation, there has to be a way, and here it is.
First, I suggest opening a profile for GTA V if the Crimson software hasn't already. The below setting will remove all the significant stuttering possible (from my test) while maintaining the highest possible picture quality, please start by following it closely and then fine tune it to your liking. (I cannot guarantee my setting are all correct, let me know if you spot something fishy)
Anti-Aliasing Mode: Use App Default: Use App
Anti-Aliasing Method: Multisampling Seems to help with micro-stuttering, not critical
Morphological Filtering: OFF Default OFF
Anisotropic Filtering Mode: Use App Default OFF
Texture Filtering Quality: High This will help with showing the texture correctly. I had instead bad experience with Performance setting.
Suface Format Optimization: OFF Default was ON, this setting should not be helpful towards DX11 games (but for DX9 games)
Wait for Vertical Refresh: OFF Default OFF, one big source of stuttering is VSync
OpenGL Triple Buffering: OFF Default OFF. If VSync is not used^, you cna leave this offf.
Shader Cache: AMD Optimized Default AMD Optimized. This seems to help with stuttering a bit.
Tessellation Mode: Use Application speificied Default AMD Optimized. Critical. Setting this to Use application specified REMOVED the transparent artifacts in game completely.
AMD CF mode: AFR Friendly Default: Default. I initially thought Default = AFR Friendly otherwise OFF, but it appears to help by forcing it to go with AFR Friendly.
Frame Pacing: ON Default ON. Necessary for Crossfire smoothness.
FRTC: 140 FPS (for 144Hz monitor) Anything below your monitor's FreeSync range if that's the matter.
[All High or Ultra, which ever is the higher setting]
Grass Quality: High (serious lowering FPS for everything)
FXAA: OFF One big source of stutter. I turned it ON with 2X MSAA, it stuttered. In the same game session, same position, I turned it off, turn MSAA to 4X, smooth like butter.
MSAA: 4X Default None. This is basically what RX 480 CF can do. There might be scenes with FPS hitting 40 FPS, if smoothness is what you want to ensure, go with 2X.
Reflection MSAA: 4X Same as above/
All maximum except for resolution scaling (the bottom most setting).
High details streaming when flying: OFF (serious lowering FPS is detected on flight)
Let me know if this helps.
The above really made the game run like a dream for me.