Computers have been shrinking years and this has accelerated in recent times, A Mini PC is a desktop computer in a small case that takes up very little desk space. There are numerous Windows mini PCs, and the Mac comes in a mini model as well. Configurable with the same CPUs and capacities as full-size desktop computers, a mini PC has no internal expansion, much like an all-in-one computer where all components are housed inside the monitor case.