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Nehalem Cores vs. Clock Speed: Photoshop Benchmarks
These are diglloyd benchmarks testing the speed of Photoshop on various jobs of various sizes.
diglloydSpeed1 takes 8% longer with the 8-core. Both machines has 24GB.
diglloydMedium takes 14% longer with the 8-core. Both machines has 24GB.
diglloydHuge is a “best possible”: the huge advantage of the 8-core is due to having 64GB of memory, versus 32GB for the quad-core. It shows clearly that for really huge jobs, the 8 core machine is far preferable, simply because up to 64GB of memory can be installed.