Power Consumption and Noise
Before we bring this article to a close, we'd like to cover a few final data points. Throughout all of our benchmarking and testing, we monitored how much power our test systems were consuming using a power meter. Our goal was to give you all an idea as to how much power each configuration used while idling and under a heavy workload. Please keep in mind that we were testing total system power consumption at the outlet here, not just the power being drawn by the motherboards alone.
This first graph shows the power consumption of each motherboard, when outfitted with identical supporting hardware (Core 2 Extreme QX6850, 2GB RAM, GeForce 8800 GTX). The nForce 790i SLI Ultra based motherboard consumed the most power here, especially under load where the ASUS Striker II Extreme used more power than even the 3-chip nForce 780i SLI.
This next graph represent the total system power consumption with the different graphics cards installed. While idling, the Radeon HD 3870 X2-powered system consumed the least amount of power, but under load the Radeon shot up to near the head of the pack; only the GeForce 8800 GTS 512MB SLI configuration consumed more. If you focus our attention on the GeForce 9800 GX2 specifically, you'll see that despite being powered by two GPUs and 1GB of RAM, the GX2 consumes only slightly more power than the GTX.
Finally, we'd like to comment on the GeForce 9800 GX2's noise level. While at the Windows desktop or during light gaming, the GeForce 9800 GX2 is near silent. In a typical system, we doubt the card will be audible over the average CPU cooler or PSU fan. When running under a heavy workload, however, the GX2's fan does spin up to an audible level, but we don't consider the card to be loud at all. And it doesn't product any annoying high-pitched whine either.