system unit

from The Free On-line Dictionary of Computing (8 July 2008)

system unit

   <hardware> The main body of a computer, consisting of a
   plastic or metal enclosure, the {motherboard}, and (typically)
   internal {disk drives}, a {power supply}, cooling fans, and
   whatever circuit boards plugged into the mother board, such as
   a {video card}.

   The system unit is occasionally referred to as the {CPU},
   though this really means {central processing unit}.

   (2000-08-10)