Did you install anything that will cast a overlay when you play Ark?
Something like Raptr, which comes with AMD catalyst package.
If so, try uninstall it, that's how I fixed my crashing problem.
PS. According to this:
Seems like a problem with DX11 games.
If you have installed the driver 15.20 from the cd that came with your 390x, uninstall it using DDU (in Windows safe mode).
Then install the newest driver 15.15 from the AMD website.
So far this solved my problem with GTA5 @dx11.