To be honest you need to study this for yourself. Mobos come in all forms and usually you pick one for the CPU and affordability. This link may be useful, just to get started, but start with the CPU then motherboards that support it. Check sockets,ram slots and compatibility, physical size for supporting GPU cards etc. ATX or mATX and so on.
Honor 5X review: Hands-on with the new budget phone from Hauwei's young brand