Motherboard
The motherboard must meet your requirements. For example, if your project needs additional power, then you should buy a motherboard with support for two processors. It all depends on your needs and what you are going to host on your server.
As an example of a motherboard, I can specify the following:
MZ71-CE0 (rev. 3.x)
MZ72-HB2 (rev. 3.0)
Asus P11C-M/4L
Processor
Since this is a server, we take job function email database processors with at least 8 cores. These types of processors can be considered the most affordable and convenient for work. Again, you can buy two processors for your server. However, if you need two processors, it is better to install processors with more than 32 cores.
Examples:
Intel Xeon E-2174G
Intel Xeon W-1390
AMD EPYC 7443P
RAM
RAM is an important element in the operation of the server and computer. As a rule, the more RAM the faster the information will be processed. Therefore, you should install at least 16 GB of RAM on the server. And again, the more demanding your project is, the more memory you will need. There are some restrictions that can be imposed by the OS itself that you are using.
Examples:
Samsung RDIMM 32GB 2Rx4 DDR4
Micron 32GB DDR4 3200
Video Card (Optional)
For some kind of servers, a video card is a mandatory attribute. It can be used to process graphic information, for example, to process video. If suddenly you have a game server, then you will need this attribute for speed and smoother processing of information.