So not overclocked at all? Do you use AMD turbo ? doom likes to run on a steady cpu and turbo going up and down causes me issues...
(unfortunately I can't offer you any real advice on Nvidia cards. I've never had one yet. lol) obviously vsync won't do you much good if you aren't exceeding your monitor refresh rate since vulkan eliminates screen tearing on it's own. That up to 90fps in vulkan is pretty useless on my 60fps monitor!
Sorry I can't give you really helpful advice. 90% of freezes and crashes In Vulkan mode seem to come from turning around quickly or opening a door, which generally indicates an issue under sudden load (I.e voltage/clock problems.) soooo
Oh, I forgot to ask, is your card a 2gb or 4gb model?