A small-form-factor PC needs a motherboard smaller than microATX. Which form factor on a desktop board list fits that case?
Select an answer to reveal the explanation.
Short Explanation
You need a smaller floor plan, not a bigger one and not a memory stick. ITX is the compact motherboard family that fits when microATX is still too wide. ATX is the large board, and a drive size or a laptop memory module is not a motherboard shape.
Full Explanation
ITX boards, commonly Mini-ITX in compact cases, are smaller than microATX boards. A case that cannot take microATX can still take an ITX board if the case is built for it. ATX is larger than microATX, so it is the wrong direction when the case is already too small for microATX. A 3.5-inch measurement is a hard-drive form factor, not a motherboard. SODIMM is a laptop memory module. It is not a motherboard form factor. Exam caveat: the case, the power supply, and the cooler still have to match the ITX board. The form factor only answers the size question. Operational check: compare the case's stated board size with ITX, confirm the standoffs match, and do not force an ATX tray into the compact chassis. Measure the case tray against the board before you order, and match the power connector the ITX board expects. Confirm the cooler and the power supply also clear the compact case before you close it. Check the standoff map twice so a spare post does not short the board. Seat the board only after every standoff matches a hole.