RobertXu

http://www.tomshardware.com/howto/20050713/index.html
Analysis

There are several things that are put straight by this review:

AMD systems are generally much more energy-efficient than Intel-based computers. We measured idle power consumption numbers of 90-112 W for the Athlon 64 system while the Intel computers consumed between 115-157 W with dedicated graphics.
From a performance per Watt point of view, Pentium-based computers perform far worse under a heavy load due to the higher clock speed level. A maximum of 166 W under 3DMark 05 (Athlon 64 4000+ with nForce4 Ultra) is much more acceptable than 255 W (Pentium 4 660 with 925XE).
There are obvious differences between the available chipset options. Yet they are difficult to determine due to slightly varying clock speeds, differences in voltage regulators etc.
PCI Express chipsets seem to draw more power than AGP core logic.
Conclusion

The question whether to buy an AMD or Intel system will continue to depend on a careful benchmark study, the type of applications you plan to run and personal preferences. However, energy costs are something we recommend not to leave out of your considerations any more.

While the impact on your energy bill of either a low-end or an enthusiast machine will not be remarkable at places with low energy prices ($0.10 per kWh and below), it certainly reaches a critical mass with rising prices. Differences can be extensive enough to create an annual energy cost difference of a few hundred dollars!

Just take some time and think about the cost difference as soon as you need to run several computers... or several hundreds.
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