Computer Cabinets, size for efficient heat xfer Options

[grumpy]

I want to build sealed enclosures for my computers because of dust problems; our heating is from a wood burner, and evenworse, I'm considering using my wood workshop part-time as a studio. Nuts?
probably. I'm thinking of making sealed metal cabinets out of 5mm mild steel perhaps with fins on the inside to make it transfer heat more efficiently. I don't want to use fans/filters because of noise. It seems to me that it would work but how large do I make it? Has anyone experience of anything like this, or any ideas on whre to find info? Iknow you can buy filterbags to cover everything but they wouldn't do anything about noise, and anyway Heath Robinson didn't where he is today (6 foot under, thinking about it) by buying filterbags. Thanks.