Benchmark Testing & the Need for Speed; HP Z600 workstation Speeds up Toolpath Calculations

This is a meaningless comparision. Because dissimilar CPU architectures are compared, it in no way substantiates the claim that 8 cores are better than four.
A meaningful comparison would have been the Z600 with one quad core CPU versus the same workstation with two quad core CPUs. My guess is that there would be vitually no difference in performance and certainly not enough to justify the 300% higher cost of a dual CPU Z600 and a single CPU Z400 running at the same clock speed.

Comparison effort is good and informative... but I repeated the same test on a whole range of CPU, VGA and RAM configurations. Coincidentally test cases included a QX9300 CPU and a Q9400 CPU. It turned out that :
a ) Single Core i7-860 and Corei7-870 CPU s have the same times as reported in this review - furthermore, with MultiThreading enabled, there was a slight drop in performance ( around 0,3 %) compared to Multithreading disabled case.
b ) Higher clock speeds lead to higher performance.
My review is Turkish, but you can download the raw pdf data too and compare the results.
http://www.muhendispc.com/index.php?option=com_content&view=article&id=106:pm2010perf&catid=43:powermill&Itemid=94