From Jonathan Gardner's Tech Wiki
The various components fit together in the following way.
- Motherboard: This is the heart of the operation. Choose a good motherboard, and everything else will fall into place. The motherboard will limit pretty much every component out there.
- CPU: The CPU is the brains of the operation. Nowadays, a fast CPU isn't necessarily better, however. The CPU plugs into the motherboard directly and usually requires its own heat sink.
- Memory: The memory stores short-term memory. It needs to be fast and big for a comfortable system. It plugs into the motherboard directly.