I've found our current xeon E5-1660v3 (and lesser versions) suitable for my needs so I can't speak to AMD setups or performance. For OP I'd recommend a decent xeon server and as much storage and RAM as you think you'll need to grow, you can run as many forums as you like until it can't take anymore. I wouldn't spend more then $100 on it. Even less if you have low traffic. Add Nginx, mariadb and php-fpm, backups and away you go.I personally am not a big fan of using desktop chipsets for my "big iron" if I'm going to jump into a dedicated server option... and the majority of those AMD Ryzen 5xxx chipsets are, at their core, simply desktop chipsets... and there IS a difference between server level chipsets and desktop chipsets.