Like I've said before, PC's are made up of components as a whole they're pretty expensive, but individually they're reasonable. Lets say I burned up my P4 - the replacement (see link below) is available for $248 not a real budget killer. Maybe for a struggling college student paying his way, but I'm well past that point in life.
Anyway in the bios I have several parameters setup If CPU temp goes goes high _ system shuts down. If the collant pump or radiator fan stops (monitoring pump & fan rpm) the Area 51 shuts itself down - very little chance of needing a warranty when its set up correctly.http://www.starmicro.net/detail.aspx?ID=547