Some Cons:
1. There is no use for a "server" if you don't have good internet.
2. Hosting a website out of your house will not work unless you buy a static IP and get more bandwidth.
3. You don't have to buy a "server" to get a good hosting computer.
4. It's a server designed for business use. Might be fine for a web host, but after looking at the options, you're probably going to have to pay $700 for a model that would be worth hosting games on.
But I think a server would be more reliable and might be friendlier on power use.