ITX boards and SFX power supplies are certainly less common, but by no means hard to find. And they are standardized, just like the ATX board variants and ATX p

ITX boards and SFX power supplies are certainly less common, but by no means hard to find. And they are standardized, just like the ATX board variants and ATX power supplies. The only compatibility issue that you need to worry about is cooler height and video card length, if you choose a very small case. But there are plenty of really nice ITX cases like the NCASE M1 that are reasonably small, with excellent compatibility. If you want to get really exotic, there are cases that require DC to DC adapters for external power supplies, but if you stick with SFX internal PSUs you should be fine.