Intel has placed a large amount of emphasis on the Intel Core 2 Duo line of processors' low power consumption levels. As Intel explains in their introduction to the Core 2 Duo architecture, they believe the processors offer high performance at low levels of power consumption.

The following table compares the declared TDP values of Intel processors against AMD processors:

Intel's declared TDP (Thermal Design Power) values are not the maximum consumption levels of the processors. Instead, they are the typical TDP the processors reach in what Intel believes is a typical situation. AMD's figures, on the other hand, are the maximum consumption the processors can have in any situation. This is something very important to keep in mind when reading TDP values of Intel and AMD processors.

Moreover, the TDP value supplied by AMD also includes the integrated memory controller. For Intel processors the memory controllers aren't integrated in the CPU. Instead, they are external and located on the north bridge. For this reason we have tested the entire power draw of the system, using the same parts where possible:

• motherboard: Asus M2R32-MVP ( ATI Crossfire Xpress 3200 chipset)
• motherboard: Intel D975XBX2KR ( Intel 975X chipset)
• memory: Corsair CM2X1024 6400 (5-5-5-15) @ 800 MHz; 2x1 Gbyte
• hard disk: Western Digital WD1600JS - Serial ATA - 7200 rpm, 160 Gbytes
• video card : ATI Radeon X1950XTX ( 650 MHz GPU; 2,000 MHz video memory)
• operating system : Windows XP Professional, Service Pack 2
• video driver: ATI Catalyst 6.10

We tested at two power states; idle and full load. Idle consisted of an empty desktop loaded in Windows XP Service Pack 2, and "Full Load" consisted of all processors at 100% usage by running POV-Ray 3.7. In addition, all processors had power saving features enabled.

At idle, AMD's Cool'n'Quiet kicked in, which is why we see nearly identical power consumption for all AMD processors. Intel processors are nearly identical to each other, except for minor variations caused by the different L2 caches of higher-end processors. AMD's Cool'n'Quiet helped keep power consumption low for AMD processors by reducing operating frequencies to 1 GHz when the system was idle.

Under 100% the scene shifts to favor Intel Core 2 Duo processors. The Core 2 Extreme QX6700 consumes the most power, obviously because the presence of four cores increases its power needs. The 65nm Athlon 54 X2 5000+ consumes the least power out of all AMD processors, while the Athlon 64 X2 6000+ consumes the most.