the kicker from Tom's Hardware, regarding Power Consumption...
However, the Intel Pentium 4 or Pentium D systems also consume more energy in idle mode - more than the Athlon 64 or Athlon 64 X2 under maximum load.
the Pentium D system manages to burn over 200 watts as soon as it's turned on, even when it isn't doing anything. It even exceeds 310 W when working and 350+ W with the graphics card employed! AMD proves that this is not necessary at all: a range of 125 to 190 Watts is much more acceptable (235 counting the graphics card). And that is without Cool & Quiet even enabled.