Well according to the UN University (UNU) about 1.8 tonnes of material. The UNU research discovered that to produce a PC and it's CRT display it takes 240Kgs of fossil fuel, this is some 10 times the weight of the computer itself. This is very high compared with other goods. Cars and refrigerators use just their own weight during production. Additionally 22Kgs. of chemicals are used in the PC many of which have now been identified as hazardous to human health. Not to mention the 1500Kgs. of water also used during the various production processes. Not surprisingly the UNU concludes the environmental impacts associated with using fossil fuels, hazardous chemicals and water are significant and "deserve attention".
In a later publication UNU goes on to say "Extending the usable life is a very effective way of reducing all types of burdens, but relatively few older PCs are being resold, refurbished or recycled - most are stored and eventually end up in landfills."
