I also converted video, shrinking a 12GB file to a 2.5GB 720p h.264 file. That task took a mid-2012 Retina MacBook Pro with a 2.6GHz quad-core Intel i7 processor 38 minutes and 10 seconds to complete. The Mac Pro needed only 16 minutes and 32 seconds.
Hands down, this is the fastest Mac I've ever used. The kicker? This isn't even the most powerful configuration. The other kicker? The Mac Pro is faster when the software is specifically written to take advantage of technologies like OpenCL, which utilize the GPUs as processing cores in concert with the CPUs.
The real issue, then, becomes this: There's not much you can do on the Mac Pro that you can't do with an iMac. There are obvious pluses to the Mac Pro that will entice certain people, yet be overkill for some. The Mac Pro is faster (sometimes by a little, often by a lot) and it supports six monitors and every internal component is user upgradable. But to get the most out of the Pro, the software you use on a daily basis has to be written to take advantage of this hardware.
So if you're trying to decide between getting a Mac Pro or an iMac, ask yourself whether your software supports the Pro, and whether the speed gains you'll see with the higher-priced hardware is worth the extra cost.
For many, it's clearly a no — the iMac, a Mac mini or even a MacBook is plenty fast, especially considering the cost. But for those whose daily software can take advantage of the Mac Pro's hardware, who work in time-crunch environments, or who can afford an amazing-looking, brilliantly engineered computer at their desk... Well, the Mac Pro is a great machine.
Do I recommend the Mac Pro? Of course. This is the fastest machine I've ever used and it wasn't even the speediest configuration. It's also the most expensive machine I've ever used and it wasn't even the priciest configuration. The Mac Pro is recommended because of its speed, its design, and the fact that every component can be upgraded down the line (if parts become available). If you want speed, this is it.
Just make sure you justify the cost.
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