One of the real advantages of upgrading an older system to a newer 3x00 series card is the new Radeon’s superb high definition video acceleration. We know that these cards can lower CPU utilization from 100% to 10% on older, slower CPUs, so HD video playback is an ideal application for someone who wants to get more life out of an older PC, perhaps by converting it into a home theatre box.

With this in mind, we tested 1080p HD-DVD video playback on the AGP Radeon X1950 PRO, and then on the AGP 3850, to see exactly what would happen.

Some very interesting results here! First off, we have to point out that the solid red line at 100% isn’t the top of the graph; it’s CPU utilization with the X1950 PRO. What’s worse, actual playback was in the 1-frame-per-second category on the X1950. Completely unwatchable.

The wavy green line between 90% and 100% CPU utilization is the Radeon 3850. Clearly, while it is offloading a ton of work off of the CPU, there is still a performance limitation here. This is probably a combination of the CPU and the AGP bus slowing down communication between the graphics card and the rest of the system.

Having said that, while the CPU utilization level isn’t pretty, the movie played well enough—it was very watchable, and for the most part appeared perfectly smooth. There was a hiccup at the beginning where it faltered a little, but it recovered, and although we scrutinized the playback for problems afterward, we didn’t notice any.

Clearly, the Radeon 3850 is a viable choice for those who would like to turn their old rigs into home theatre PCs; the only question is whether the AGP 2600 XT would be capable of the same feat for much less cost. We assume it would work, but without an AGP sample of the 2600 XT available for us to test, we can’t be 100% sure.