4 core vs 8 core

Something else to consider besides the CPU speed between 4 and 8 is the maximum ram. 4 Cores can get you up to only 8GB but 8 cores allows up to 32GB. More Ram certainly helps the apps you listed.

As far as benchmarks, once all the various configurations start shipping, there will be plenty of sites running comparisons. So my advice is to wait and see,

The latter will be nearly twice as fast as the former and can accommodate twice the RAM. It also has a higher end version of the Xeon processor.

Initial benchmarks have been posted at Bare Feats.

After Effects with multiprocessing enabled spawns a subprocess for each core. We've seen a dramatic difference in the render speed of 4-core vs 8-core because of that.

In addition, each process can use up to 3GB of RAM. So having 8 memory slots in the 8-core is an added advantage.

The same is true of Compressor (which is part of Final Cut Studio). The Apple Qmaster can be set create a virtual cluster with as many instances as you have cores. Each instance is a subprocess that can grab up to 3GB each.

Only certain functions/filters in Photoshop use multiple cores. But Photoshop is able to use more than the 3GB memory cache defined in preferences. If you overflow that and there is memory to spare, OS X Leopard will allocate unused memory as a virtual scratch volume. If you are editing RAW photos with lots of layers and lots of history states, having the 8 memory slots on the 8-core is a big advantage.

Motion works in a similar way. Just try doing a RAM Preview -> Play Range on the 900 frame Blocks-Detail.HD template and use Activity Monitor to see how much RAM is used. In fact, unless you have at least 8GB of RAM, it won't render all 900 frames in RAM.

Message was edited by: rob_ART to correct typos