Over the last few years HP have had deals on Microservers, which means a lot of people have GEN8 servers around.
These micro servers have a lot of expansion, you get a generic cheap 2 core processor that you can update to an 8 core if you look carefully everything else is pretty good.
Now with the release of RedHat/Centos 8 there are now problems with the software raid controller, HP havent released a driver for it, so you can use the controller in native SATA mode, but raid wont work. A way to get around this is to purchase a cheap HP p410/p420 raid card from Ebay, put that in the free slot and plug your sata drives into it.
Ok you loose the slot, but the microserver has an extension to its life.