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2 of 2 people found the following review helpful:
5.0 out of 5 stars
2+2=4??, 1 April 2005
First I must admit to bias: I've got this machine, and it's great. Second, I'd like to add to the 2GHz/4GHz question. The performance of a multi-processor machine depends on several factors, the most salient of which include the operating system, the extent to which a particular programme is optimised for multiple processors, and the extent to which a particular processor family scales in multi-processor environments (for example, an Intel Xeon performs better here than a Pentium, which is why multi-proc wintel machines tend to use Xeon). In the case of the G5 described here, the operating system, being based on Unix, makes good use of multiple processors. The G5 chip family scales very well in multi-processor installations with up to 4 cores, far better than pentium (which is a poor multi-cpu chip) and probably better than Xeon. However, most software for the platform isn't (yet) especially optimised for multi-processors. Ideal situations show a possible scale of at least 80%, meaning that dual 2GHz processors would perform at about a 3.2GHz level on a single well written app. Examples of this include some optimised operations in photoshop. More typically for single app you'd get a speed boost, but not that much. However, the big advantage of multiple processors is when you run multiple applications. Thus for example the operating system might use one processor, and a video editing app might use the other, and this also gives a big performance boost. I tend to have about 15 applications open at once, and can rip a DVD in the background while using another app in the foreground without any degradation in performance: that foreground app is probably not performing any higher than it would running alone on a single processor 2GHz machine, but then on a single processor machine I probably wouldn't be able to rip a DVD at the same time ;-) The bottom line is this machine has ample performance for almost all tasks, including real time video editing effects on HD video (using Final Cut Pro). Using the CPU usage graph included in the operating system, it's remarkable how well balanced the usage of the two CPUs is under load, but also remarkable that I've never seen the machine go above 80% CPU usage (although I haven't ripped a DVD and done HD video editing at the same time, that might do it!).
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