What components make up an SFFPC?

  All computers require the same basic components as conventional computers, namely the:

• CPU
• CPU Cooler
• Motherboard
• Memory
• Storage
• Power Supply

So, how are these components different?

  In an SFFPC, these components function the same, but cut the clutter and are scaled back to the basics. Don't be fooled by the simplicity of this solution, as these size-reduced products come with a whole slew of problems.
  As we scale down our components, we face the problem of adhering to standards. In a conventional computer, aside from matching motherboard sockets, (where each socket standard much specifically matches the CPU), our hardware will most likely fit together without any problems. The RAM sticks go where the RAM slots are on the motherboard, the storage connects to the applicable storage ports on the motherboard, and all the components nestle safely in their standardized case.
  As we proceed to change the size, the compatibility changes, most noticeably in the motherboard to case relationship. When we move to a smaller motherboard, small things change, like the number of RAM slots, which decrease from 4 slots to 2, forcing us to consider the type of ram we use and the amount of it. Likewise, when we move to a smaller case, we need to make sure all of our components can physically fit.
  Making products for a niche audience has its problems for manufacturers too, and economies of scale indicate that with the smaller demand, we see higher prices and less convenience for stock and amenities. Where a standard size motherboard may have a standard price, the factors towards its smaller counterpart combine, overall resulting in a motherboard that will usually cost the same, despite having fewer amenities, and less physical material.
  This point stands for laptops too! The cost for maintaining a laptop is significantly higher, as the entire product is custom to the manufacturer, meaning that almost none of the parts on a laptop can be fixed with standardized components, and the tooling costs of creating an all in one solution will result in an overall smaller solution, but will NOT have the affordability, upgradability, repairability, or power to suit the needs of an SFFPC user.
  TLDR: Weighing in all the factors, building an SFFPC can mean compromising on some features, and risking compatibility, but this will yield to a machine that suits the needs of an SFFPC user much better than a traditional computer can.