Total System Power Consumption
We'd like to cover a few final data points before bringing this article to a close. 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.
As you can see, the Radeon HD 4870 X2 isn't going to end up in any "green" PCs. When either idling or running under a heavy graphics workload, the Radeon HD 4870 X2 consumed more power than another single graphics card, and sometimes more than two single-GPU based graphics cards. The 4-GPU, Radeon HD 4870 X2 CrossFireX configuration also consumed more power than any other graphics card configuration by a large margin.
As you probably expect, a graphics configuration that pulls total system power consumption up into the 820+ watt range can get quite hot and run somewhat loud. We witnessed GPU temperatures over 90ºC according to ATI's drivers with the cards running under load, and idle temps hovered around 80ºC. We wonder just how accurate the reporting in the driver is, however, as we also recorded heatsink temperatures using an infrared thermometer of about 78ºC. Regardless, one thing is for certain--the Radeon HD 4870 X2 can get very hot. We definitely recommend good case cooling if you plan to purchase one of these babies.
When running under load, the cards' coolers also produce a very noticeable report. In a single card configuration, the Radeon HD 4870 X2's acoustic profile is about on par with other high-end graphics cards, and even though it was a little louder, we wouldn't consider it bothersome. With two cards cranking along at nearly full bore, however, the noise output would definitely be a concern for some.