They have 3 USB3.0 ports on the rear, and two more on the front. The heart of my PMS system is a Lenovo Thinkcentre M93p Intel Core i5-4570T CPU 2.90GHz 16GB RAM 256GB SSD. When you buy a NAS cage, part of what you are paying for is aesthetics. There is frankly no need to have your system out on public display, you can hide it behind books on a bookshelf, as long as you provide it with good airflow - this is important because it means I could build a system with as much mess of boxes and cables as I needed without concern for aesthetics. I definitely didn't want PMS running on an off-the-shelf NAS (they are far too underpowered), and I didn't see the need to have all my storage on an off-the-shelf NAS. I am very familiar with NAS's, have had them for about 20 years, and I contemplated buying another NAS specifically to run PMS, but I realized that I would rather have as much optionality in my system as possible, and so that meant build my own. This advice is not only for PMS but also for the client devices. One great piece of advice: use software and hardware for which there is an already large Plex user base, because not only does that mean someone has already solved any problem you encounter, but that the Plex developers spend more time on getting things to work well for the popular devices and servers than for the less popular ones. So I spoke to a few friends who had been running PMS for many years and I copied my build off of theirs with a few modifications. I started in the same place as you, not sure what Plex is, not sure how much media content I would have, not sure what devices I would play Plex on, etc.

This build is not for massive hoarders of media (200TB, etc), it's for the average PMS user, so please keep that in mind in the comments. This build is for the average user, the person with home use and maybe a few remote users. However, the answers in reply to the noobs are almost all from users who are effectively competing with Netflix in terms of hardware power and such. I've been in on this forum for a few years, and there are thousands of questions from noobs about how to buy or build a NAS for Plex Media Server (PMS).

Plex server build