You need to determine what you want this server to perform. Keep in mind that objective is to make a system that is capable of fulfilling your needs, considering the server OS and supporting of applications. It’s the software installed in the system that fulfills your requirements, and not the system itself.

The motherboard/CPU combination specials are better alternative as they are pretested for compatibility, so there’s not much research is needed form your side. But one still requires to do check every part, from CPU to the memory and the chipset on the motherboard, to decide whether there’s plenty suppoSWrt for expansion. This motherboard can support up to a 1GHzCPU, leaving enough space for expansion. If required more, option of later upgradation is always available.