I bought a new RX 580 to feed my new LG Ultrawide 38UC99 and everything works nice, sharp and smooth on the Display port connection.
There is 1 issue however. When using the sound connection on the display port, it gives cracking sound every now and then. Especially when there is some extra processing going on.
I've tried everything to fix it, changing cables, changing slots to changing memory.
In the end I had to conclude it had something to do with the Video card itself.
I nailed it down some power settings that I can tweak (Global wattman).
To my surprise, the issues are gone when I set the minimum state to State 1 instead of the State 0.
Unfortunately, these settings are lost after every reboot.
Can you provide a trick or an update to your software to bypass this issue? It seems that your minimum settings are not stable enough for widescreen usages.
You should be able to save that setting to a profile. That profile should be kept. I know of 2 instances that will default back. One is when you update a driver it will default and two is when the driver crashes it will go back to default. Just reload the profile you saved.
If Windows is not retaining this new setting it may be because it is still referencing old information on startup. Disable "Hibernation" and "Fast Startup" in Windows 10.
When you are in Wattman I would suggest you slide that Power Limit slider over to the right to it's maximum also (+50). That will likely keep you from having to come back with some other common issues.
Good Luck and Congratulations on the new card, I have the same one! Enjoy that monitor too!