One of the main environmental considerations when creating computer systems is whether to upgrade an existing system or replace it with a new one.
Power consumption - Modern computers tend to be smaller and more efficient, as well as having better 'sleep' systems so they use far less power when not in use. Modern computer systems usually include a LCD monitor which have 1/5 the typical power consumption of older cathode ray tube (CRT) monitors.
Health risks - discarded computer equipment is usually either dumped in landfill sites or recycled, often in poorly managed facilities in developing countries. Some of the hazards include:
Refurbishing/upgrading - this can often be a better option than throwing it away, the majority of computer systems disposed of are far from their real end-of-life and could go on to give as much as 6,000 additional hours of use with motherboard, RAM, CPU and hard-drive upgrades.
Sending to developing countries - many charities will ship old computer equipment to countries in the developing world where 99% of children leave school without ever having seen or touched a computer in the classroom.