es:

A couple other problems with the 486DX/50:

1.)  System manufacturers had MAJOR problems solving the electromagnetic 
interference problems with 486DX/50 systems.  Getting an FCC-B (home use) 
certification required additional shielding in the system.

2.)  HEAT...a lot of people seem to be installing heat sinks and/or cooling 
fans on their 486DX2/66 chips.  I would guess that the 486DX/50 ran 
temperatures inside the case even hotter.  And heat is the enemy of system 
reliability.

Ed