Windows XP CPU utilization
Since many enthusiasts have balked at moving to Windows Vista, we threw the cards through a quick round of CPU utilization tests in Windows XP. Here, we can enjoy the full benefits of DirectSound hardware acceleration without Vista's Universal Audio Architecture getting in the way.

Even with 2D audio, the benefits of hardware acceleration are immediately apparent. The X-Fi cards register the lowest CPU utilization of the lot, and even the Realtek onboard audio uses fewer CPU cycles than the Xonar.

Throw 3D audio into the mix, and the X-Fi cards continue to consume much fewer CPU resources than the competition. The ALC889A is a little closer to the Xonar here, but it's still more efficient than Asus' swankiest sound card. At least the Xonar registers support for more than 32 concurrent 3D voices; the ALC889A does not.

The picture doesn't change much when we add EAX to the equation; the X-Fi-based solutions still dominate, leaving the Xonar in their dust. Even when processing 128 simultaneous 3D voices, the X-Fi cards still use fewer CPU cycles than the Xonar does when handling just 32.

Power consumption
Power consumption has become a staple of our hardware coverage here at TR, but it's not something we normally tackle with sound cards. However, the Xonar's auxiliary power connector had us worried, so we busted out a Watts Up? Pro power meter and measured total system power consumption, sans monitor and speakers, at the wall outlet. Systems were tested at idle and again while playing an MP3.

Phew. The Xonar may require a four-pin floppy power connector, but it consumes about as much power as the X-Fi Prelude. The Fatal1ty card pulls slightly less juice, but when compared with the same system running its integrated audio, the power draw of our discrete sound cards amounts to less than 10 watts.