FWIW, we're not talking about how many PC power supplies fail, but how many
fail in such a way as to burst into flames and set fire to the surroundings,
which puts the probability figure way down.

In a company with several thousand PCs, many of which are no-name clones and
few of which are ever turned off (many sitting in labs unattended and unused
for weeks or months at a timer), I don't think we've ever had a fire...

BillW