I recently bought a HP ProLiant DL140 G3 Server server and want to convert it to a tower case.
I am looking at HENBRO SR20969-CO. Before I spend cash, what are some of the potential problems I might run into converting it?
Most caes that you purchase will support ATX format motherboards (or Micro-ATX or mini-ATX etc).
The motherboard in the DL140 is not a standard ATX format. There are several things that make putting it in a standard case difficult.
Basically, it isn't going to fit right. I imagine your main issue is with the noise, so perhaps the best approach would be to mount the server with the lid off, inside a custom case, where you can house a standard PSU and system fans.
Instead of going through the hassle of doing that, I would recommend you get a rack case and convert to rack equipment, as it is much neater and saves space, once you have more than a couple of computers.
I actually do the opposite and put pedestal servers into Antec rackmount cases, as pedestal servers are usually cheaper, and nearly always a lot quieter (eg. I have done this with the HP ProLiant ML110 G5, ML115 G5, and ML350 G6).
You can get small rack units of around 10U (the very small ones are not deep enough for servers, only networking equipment) with glass doors and veneered top surfaces, and even insulation padding, so they can fit into a home or office very nicely.
You can even make a rack case from a cheap 'Lack' coffee table from IKEA. Here is a website about that.