Your hardware appears to be well over requirements even if they were dramatically increased.
Please try a full clean re-install:
- move any valued save games elsewhere
- "delete local content" in Steam-CK2
- manually delete all files and folders left under Steam/CK2 AND Documents/Paradox/CK2
- re-install game in Steam, run a Steam Verify when done.
IF that doesn't help, Please post a dxdiag.txt (you can delete everything after the end of the "Sound devices" section for brevity) and your Documents/CK2/settings.txt. From your Documents/Paradox/CK2/logs/ directory, post system.log . Open setup.log in notepad and search for 'checksum', post that line only here too please.