Power Consumption & Noise
We have a few final data points we'd like to cover before bringing this article to a close. Throughout all of our benchmarking, we monitored how much power our ATI based CrossFire test system was consuming using a power meter, and also took some notes regarding its noise output. Our goal was to give you all an idea as to how much power each configuration used and to explain how loud the configurations were under load. Please keep in mind that we were testing total system power consumption here, not just the power being drawn by the video cards alone.
While idling, either CrossFire configuration drew only marginally more power than a single card configuration. Under load, however, power consumption goes way up - as expected. A pair of 512MB Radeon X1800 XTs running in CrossFire more used nearly 370W of power. A Radeon X1800 XL CrossFire configuration peaked at just over 340W. Clearly, running two Radeon X1800s in CrossFire mode requires a significant amount of power, so make sure your PSU is up to snuff should you be in the market for X1800 CrossFire.
We should also talk a bit about the noise associated with running a pair of X1800 XTs in a single system. When we first setup our test machine, and powered it up for the first time, it was clearly the loudest system that had ever graced the lab. Upon initial startup, both fans on both X1800s rotated at their maximum speeds, which resulted in a lot of noise. Once the drivers were installed, however, the fans on both cards spun-down dramatically and the test system became relatively quiet. Then, throughout the rest of our testing, the fans never spun up to maximum again. To put it simply, except for the initial shock of hearing two X1800 XTs running at full-bore when we first turned on the machine, our X1800 XT CrossFire test system was relatively quiet, and we would not consider excessive noise an issue at all during normal use.