Leaving PC's on & Assoc fire hazards

[#1]

I've seen a couple of PC fires where the machines were under a desk and not cleaned during a few years of usage. When the box eventually overheated the dust inside the case caught fire and led to the evacuation of the building. One of the PCs was used by the Finance Director's secretary, who had refused to upgrade the PC or to pay a monthly service fee - to save money. Thereafter replacing out of date PCs was suddenly a lot less difficult, and the FD started to pay his share of technicians costs.

[#2]

IMPO and partially in my own experience the circumstances for a PC malfunctioning in someway which could then start a fire would be pretty rare indeed as there's nothing inside a PC that's incrediby flammable. So I suppose it would depend on where your PC is situated and what sort of environment you're in. If you have a dodgy old PC and a fetish for collecting polystyrene packing chips or kindling you'd be in trouble I guess One for Jamie and Adam on Mythbusters/tested.com I reckon.

[#3]

Continuing Adam's theme, how about a PC housed in a matchbox with surrounding matchboxes containing matches ?

or using a petrol pump as a PC case ?

or perhaps a barbecue ?

[#4]

A wooden one?
I think the main objective is to minimise the risk of any fire spreading and agree with Adam's sentiments.

[#5]

Or a cardboard box!:

[#6]

The fluff that collects in fans etc. is a hell of a lot more ignitable than wood or even cardboard, keep your PC clear of fluff then it's going to be a minimal fire risk (though I'd still recommend a metal enclosure rather than wood or card).