New eight core Mac Pro performance mixed bag
 

Cinebench ran 45 percent faster than on a similarly equipped quad core system, keeping all eight cores busy in the process. Geekbench, on the other hand, was 56 percent faster with only 600 percent out of the maximum 800 percent CPU usage. Photoshop CS3 and Aperture 1.5 did manage to push the CPUs to 796 percent, but the performance increase was in single digit percentage points for tests with both applications.

http://arstechnica.com/journals/appl...ance-mixed-bag