Power Consumption and Acoustics
Before we bring this article to a close, we'd like to cover the topic of power consumption. As we mentioned earlier, 3-Way SLI is not for those looking to pinch pennies on their electric bill. Throughout all of our benchmarking and testing, we monitored how much power our test system was consuming using an in-line power meter. Our goal was to give you all an idea as to how much power each configuration used under load. Please keep in mind that we were testing total system power consumption at the outlet here, not just the power being drawn by the video cards alone.
The graph above puts things into a perfectly clear perspective in case there was any doubt in your mind. A 3-Way SLI setup with three NVIDIA GeForce 8800 Ultra graphics cards installed uses an enormous amount of power. Granted, the system is fairly well-equipped with three standard SATA hard drives as well but even at their peak draw, three hard drives consume around 30 - 35 watts on average. The rest is all power consumption for system memory, motherboard, main processor cores and graphics processors. Peak power draw for a GeForce 8800 Ultra is somewhere in the neighborhood of 175 Watts; that's 525 Watts for the graphics subsystem alone. What's interesting is how power consumption scales from our standard 8800 Ultra SLI two-card setup to 3-way. If you look at peak power for the standard SLI setup (578W) and then add another 175W for one more GeForce 8800 Ultra card, you come up with about 750 Watts. However, the 3-Way SLI power consumption reading we took was about 50 Watts higher than that, indicating that power consumption requirements for the system (chipset, main CPU and RAM) was also a bit higher as well in the 3-Way setup.
Acoustics are another aspect but we won't dwell too much on the subject here. If you're considering this type of setup, you're not nearly as concerned about quiet computing. It's no surprise that this high-end Maingear system was generally louder than most systems we have in the lab or on the test bench currently. In fact, the power supply alone contributed to much of the noise output of the system, in addition to multiple 120mm case fans that are setup within its chassis. In reality, the GeForce 8800 Ultra cards only spun up to the point where they were noticeable, under extremely heavy loads.