I think two points were that if it's running cold, and if it is sealed against dust etc. it will run forever and ever without burning out.
As a side note, a CPU can become too cold if you get inventive with your cooling options, and that will slow down/create instablility as things that should be connected by touch get deconnected when the cold make them contract.
John Johnson - Master of Synth.Foods-Convoy|049
Hans Adler - Synth Foods escort wing