Even the kinetic energy (fan motors, HDD motors) eventually becomes heat. E.g., the moving air from fans dissipates its energy in turbulence in the room's air, and in a closed system (airtight room), the resistance to airflow (resulting in heat) must equal the pressure differential created by the fans, unless the air builds up unbounded speed. Likewise, torque to keep the HDD platters spinning will be exactly equal to frictional losses once the disks are spun up, so all power into the spindle motors becomes heat.

Even noise that leaves the system either becomes heat as the pressure waves dissipate through the atmosphere, or else do work on eardrums (mechanical energy) which eventually becomes heat as the inner ear resists the motion of the ear bones :-)