But if your task has to do a lot of interaction with memory, the advantage drops almost to nothing - as we saw with Photoshop CS3 and Aperture. That says that if the task is pure CPU, the 8-core is twice as fast as the 4-core. Its aggregate rate was 1204MB/sec (versus the 4-core's 601MB/s). We did run the "test-compute-speed" with digLloydTools (DLT) on the 8-core. By comparison, a 6-drive hard disk RAID array can easily perform at over 400MB/sec!" That’s a measly 700MB/sec per core on a quad-core machine, and only 350MB/sec per core on an octa-core machine. Memory copy speed is at best 2.9GB/sec on the Mac Pro, in spite of Apple’s highly misleading claims of 21.3 GB/sec (“maximum processor bandwidth of up to 21.3 GB/s”-bandwidth is a bit more than double the memory copy speed). It’s already a limiting factor with the current quad-core 3.0 GHz Mac Pro. He wrote, "Memory bandwidth is inadequate for 8-cores. Our friend, Lloyd Chambers, thinks there's a memory bus bottleneck for the 8-core, which he discussed back in March on his blog.
Multi-Processing (Simultaneous rendering by Final Cut Pro, Motion, iDVD, and Photoshop CS3)ģD Gaming (Quake 4, Doom 3, Unreal Tournament 2004, Halo, World of Warcraft, Prey) using three different graphics cards Special Report on After Effects CS3 running on the Mac Pros, G5 Quad, and MacBook Pro.
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