Which is an HTPC case?
HTPC (home theater PC) cases are the smallest available units on the market today. They come in various shapes from cubes to small custom shape sizes and usually require special small form factor (SFF) motherboards (like ITX, thin Mini-ITX, UCFF, and some Micro ATX). These cases are designed to fit almost anywhere - especially in your living room as a media device and are easy to transport & move around.