Top 10 energy efficient desktop PCs

5 Mac Mini
£400
110 watts
Surprisingly, Apple's much-imitated box is the most power-hungry desktop here. It peaks at 110 watts, which is nearly twice Dell's Windows alternative. Still, I've included the Mini because some people will always prefer Mac OS X over Windows or Linux. Though it uses more power than the machines here, the Mini is relatively low power compared to other Macs. A powerful Mac Pro, for example, can use nearly 1,000 watts!