I am looking to buy something used to use strictly as an NAS for my PLEX collection.
What specifically should I be focused on? Storage space, processor speed, operating system, something else? I need help deciding which route to take.
Also, if anyone can point me towards a guide as far as how to convert a two year old Dell computer tower into an NAS, I would appreciate it.
Storage space is key, as you will need a lot of space for HD content. You don’t really need a lot of processing power if your client can do direct streaming, thus eliminating the need for transcoding.
The lightweight OS would be Ubuntu LINUX. You can run it easily in 4GB of RAM. I used this setup for a while and found it very fast and responsive. The only problem is that you need to be good with UNIX and computers.
I have found the Mac to run flawlessly without any issues. I am a Mac user by default, but I stopped using the mac as a Plex server, as it is used for my studio recording.
I am currently running a server on Windows 10 Pro. It is easier to set up RAIDs on this system, so it worked out best for me overall.
NAS? Synology are probably the most popular NAS units. I was using a DS1513+ with a DX513 expansion before I built out my server. The setup I used had 10 drive bays. My new server has 14 drives. I still have the Synology, but it is only used for my security camera system at this point. It is, however, very easy to use.
Any Windows computer can be used as a NAS (file server) by simply setting up access through the sharing controls.
Thanks for the info, I have further questions if you don’t mind:
My goal is to be able to access all my movies and TV shows from any device in my home at any time. My home has a PC, Macbook, two iPhones, an iPad, an Apple TV and a Roku.
Current Equipment:
How do I make this work? The Macbook currently has the PLEX server. However, this means it needs to be on and awake whenever I want to watch something via PLEX. I don’t want to have to do that anymore. I want everything to be on demand.
It seems like the best thing might be to buy a new SSD for the Inspiron, install the PLEX server and my media to the Inspiron to use as an NAS and network all the other devices to it via a router.
Does this make sense and - better yet - will it work??
I almost feel like there aren’t enough “PLEX for Dummies” resources to help me understand how the relationship between where the PLEX server is located and how devices access the content.
Any of the computers you mention should be able to run PLEX and stream movies without transcoding, and the Mac and Lenovo should be able to transcode. The Dell might well be able to transcode too, but older computers might have problems if things get tough. What processing power does the Dell have? The processor is a concern when you are trying to transcode media, so you do need a decent processor.
These links should help:
This link will help you determine the power of your CPU: http://www.cpubenchmark.net/cpu_list.php
The computer will have to be on at all times in order to run the server, so you are definitely right there. The power consumption is really a secondary concern. 
Running PLEX on an SSD is great, as there are no moving parts, but SSD storage is pretty expensive and you will outgrow your storage quickly when ripping Blu-ray movies in uncompressed MKV containers. Personally speaking, I am running 14 hard drives, with my media storage in RAID pairs for redundancy. If you compress your media, you will be able to store more movies in a smaller amount of storage. Many people use Handbrake for this.
If you are familiar with UNIX/LINUX, using Ubuntu LINUX would be the smoothest-running server on an older PC. The OS is very lightweight, and will run easily on the hardware. The only problem is that you need to understand UNIX in order to set up your drives for NAS access. It is nothing at all like using a Mac or PC, and it does take some knowhow.
Remote access: https://support.plex.tv/hc/en-us/articles/200289506-Remote-Access
This will help you set your PC up as a NAS: http://www.pcworld.com/article/2243748/turn-old-pc-hardware-into-a-killer-home-server-with-freenas.html
