The advances between the Pentium 4 and the Core 2 processor generation are tremendous. Not only will Core 2 processors require 1:10 to complete an entire SYSmark 2007 run as compared to 1:35 to 1:40 for the Pentium D and Pentium 4 on our reference test system, but the Core 2 processors require less power in all system states. Normalized to a 3.0 GHz Pentium 4 630 (3.0 GHz), the Pentium D 830 offers a 4% increase in performance per watt, while Core 2 Quad at 3.0 GHz and Core 2 Duo 3.0 GHz offer a 3.6x and 4.2x better performance per watt ratio in our SYSmark 2007 test environment. These numbers were collected by tracking the entire power consumed during the benchmark run.
The total power in watt-hours required to complete a SYSmark 2007 run was cut in half by replacing the Pentium D 830 by a Core 2 Duo E6850 Compare Prices on Core 2 Duo E6850 . Since SYSmark isn't an extremely computation-intensive benchmark, you can expect even more dramatic differences when it comes to rendering, ray tracing, encryption or other forms of CPU-intensive workloads.
Intel's upcoming 45 nm Penryn has shown power requirements of only a few watts in idle, and decreased power requirements under load. This sounds promising, as it should result in an even lower power requirement to complete a given workload, as well as quicker completion time, which again helps to save power and reduce heat dissipation.