As insane Steampunk PC case mods go, this Frankenstein machine by D. Mattocks will take some beating. Standing almost eight feet tall, and bristling with copper piping, vintage gauges and glass indicator lights from an old navy ship, it's not so much a computer as a tribute to H.G. Wells, Dr Frankenstein and the sort of coffin Isambard Kingdom Brunel would've probably liked to be buried in.
The vent was salvaged from an old church, and now acts as the air inlet for the water-cooling system. Meanwhile everything is backlight with green cold-cathode tubes, which manage to make the Frankenstein Computer look even more ominous. Happily one of the gauges does actually show the computer temperature, though there's probably not a steam blow-off valve.