what is used to prevent the motherboard from touching metal portions of the computer case?

The component used to prevent the motherboard from touching the metal portions of the computer case is called a standoff. Standoffs are small spacers, usually made of brass or another non-conductive material, that keep the motherboard elevated and insulated from direct contact with the case. This prevents electrical shorts that could occur if the motherboard were to touch the metal parts of the case directly. They screw into the case and align with the mounting holes on the motherboard, ensuring safe and secure installation without metal-to-metal contact that can cause shorts.