I have removed OS X from my 2008 iMac and installed Ubuntu a few days ago. I switched to a new Mac in 2015, and have had my old one in my basement for a few years, and last Friday I pulled it out and did some work on it. I’m planning on using it as a server computer to replace my previous server computer, which was either the first Intel iMac or the last PowerPC iMac, which used to be my brothers. Your answer talks about what Apple says it can do and what the developers for Apple said it can do, but what about Ubuntu? 4 GB is pretty bad for a server computer, and I can’t even use all of it. I have 3000 MB allocated to my server, and being able to upgrade that would be great. I have experienced connection timeouts while using it, and there are times where it can freeze and require a computer restart to get it working again. I connected it to Ethernet yesterday, so it should have a slightly better connection, but it’s still not great.