Multi-tasking performance
The question is, how well do these high-end processors when we place significant concurrent load on them?Our first scenario consisted of running our DivX encoding test whilst playing a 720p QuickTime movie, and recording how long the encode took. Our second scenario involved running the DivX encode whilst playing Quake 4 at 1024 x 768, recording both the time taken and the Quake 4 frame rate. Our final scenario involved our subjective experience of playing Quake 4 with a batch of DivX encodes running in the background – a likely activity.
The left-hand bars indicate the standalone (multi-threaded) DivX performance, as shown in our graph on page 5. The right-hand bars indicate the encoding time with the QuickTime clip playing concurrently.
The additional load imposed by the playback of the 720p QuickTime movie adds to the overall time, obviously. What's clear is that the quad-core QX6800 is able to take the clip in its stride, adding just 3 seconds (3.75 per cent) to the overall process. Looking at dual-core results, however, shows us that the Intel Core 2 Extreme X6800 and AMD Athlon 64 X2 6000+ add 12 and 20 per cent, respectively, to their standalone times.
Here's the same graph but with Quake 4 as the measured metric. The standalone framerate on the left and the DivX-impacted average framerate on the right. The lower the impact, the better the overall performance, and the Core 2 Extreme QX6800, again, barely registers a blip in terms of performance degradation. Framerates don't tell you the full story, but the QX6800's gameplay, with DivX running in the background, was smooth once the map was loaded. The dual-core processors' gameplay was, at times, rather jerky.
Here's the graph of the corresponding DivX framerate whilst playing Quake 4 in the foreground. Again, as expected, each processor's time to DivX completion rises, due to the Quake 4 load. The percentage increase is rather more than with just a QuickTime 720p clip, but quad-core is better than dual-core with significant multi-tasking. That's a blindingly obvious statement, we agree, but the proof is there for everyone to see.
