There are several hard technical problems surrounding power efficiency of computers, but we’ve found one that is actually not particularly challenging and could have a huge impact on the energy used by home computers and low-end servers: increasing power supply efficiency. All computers, including personal computers and servers, have power supplies to convert the alternating current (AC) from the outlet to the direct current (DC) needed by the machine. Typical power supplies waste 30-45% of their input power, and relatively simple modifications can bring this waste down to 10%. […] We believe that the development of a new open standard is necessary to achieve very high efficiencies at low costs, so we have begun discussions with Intel and other vendors that we hope might lead to significantly more efficient power supplies.