We have one final data point we'd like to cover before bringing this article to a close. Our goal was to give you all an idea as to how much power each configuration used while idling and running under load.
Please keep in mind that we were testing total system power consumption here at the outlet, not just the power being drawn by the processors alone. In this test, we're showing you a ramp-up of power from idle on the desktop to full CPU load and then a ramp to full CPU and Graphics load. We tested with a combination of Prime 95 and Folding@Home on the CPU.
Intel's new Core 2 processors are significantly more power-friendly than the Netburst-based Pentium Extreme Edition 965 and even a bit more green than AMD's Athlon 64 FX-62 when coupled to an Intel-built chipset. You may be surprised to see power consumption numbers that are relatively in-line with other architectures, but you must remember that performance is drastically increased with the new Core 2 processors.
If we used the closest to apples-to-apples comparison, the X6800 / NF4 versus the FX-62 / NF 590 SLI there is a 36 watt delta separating the X6800 from the FX-62 under load. So, while not only does the X6800 use less power when running at a full load, it can complete most jobs faster than the FX-62. This is where the Core 2's power efficiency will be far superior to most other architectures. It's not necessarily the processor's peak power consumption that'll be lower, but its total power consumption over time.
While we're talking about power, we should also point out the differences between the various Core 2 compatible chipsets. In our tests, the 975X based systems used the least power, followed by the P965 and then the nForce 4 SLIX16. However, please be aware that the P965 based Asus P5B motherboard we used for testing was loaded with integrated peripherals. It's the board's additional components that resulted in the high power usage and not anything inherent to the chipset. The nForce 4 SLIX16, however, is contenting with a couple of issues. The nForce 4 SLI SPP is manufactured on TSMC's .09 micron line, but the MCP is still manufactured at .13 micron. This combination of older and newer process technology results in higher power consumption as you can see in the comparison versus the RD580. We also suspect the nForce 4 SLIX16 wasn't properly utilizing the C1E halt state, which is why the Core 2 / nForce 4 SLIX16 combo used so much more power while idling. This is an issue that will likely be resolved in a future BIOS update, however.