Bandwidth, latency, DivX
Remember that the CPU's speed and FSB is identical with each setting; memory frequency and latency is all that changes.
There's no surprise to see that the PC8500 pack comes out on top with respect to bandwidth. Running the same pack in single-channel mode also shows impressive bandwidth, which is down to sheer speed above all else. 6.2GB/s still falls far short of the supposed 8.5GB/s usable by the CPU, and this fact will help explain why high-speed DDR2 memory is effective.
Latency is also excellent, again down to the ultra-high speeds of the modules. The dual-channel setting is almost 20ns faster than a pack running at half its speed. Single-channel mode benefits from the lack of clock buffering that's required by the other modules.
There's less of a difference in our DivX test, although seconds can turn into minutes if extremely lengthy footage is to be encoded.