I think this post may sum up and be of interest to those that are wondering why many professional users, like myself, have decided to leave the Mac Pro. NOTE: I LOVE the Apple Mac Pro and have one that has been made part of my "render network" but this should be a good read for those asking the question just what would someone do with all that CPU/GPU power?
I am a 3D artist and use many high-end 3D programs that cost between $1,000-3000 each. These include Maxon Cinema 4D, Autodesk Max, ZBrush, Vue Infinite, Poser Pro 2010 and Adobe Photoshop CS5 "Extended".
Now, most of these programs are 64bit and are capable of using as much RAM as you can throw at them. Then the Xeon CPUs REALLY come into play with their multi-cores. Having two 5680 Xeon CPUs with 12 cores and 24GB of memory with an nVidia 480x or professional series graphics card with "CUDA" support and "Shader 3". These types of programs can and will eat as much as you have. If one checks benchmarks such as "Cinebench" and other render testing you will see where all of this comes into play and it is drastic the difference all of this high-end hardware makes.
What does this mean? A few things, but most important is the amount of material a single scene can handle, rather static or animated and the time it takes to render those scenes. Those two things alone make a LOT of difference in being hindered in what you can do.
The other thing it is worth noting is that nVidia is typically the champ when it comes to best performance for 3D rendering. One reason is some programs will take advantage of specific codecs and processes such as "CUDA". Going with anything other than nVidia for a 3D workstation would not be quite as good and in some cases cripple some features in select 3D programs, which if you spent thousands on is not an option.
Now, lets take this one step further to what I do. Some of those 3D software programs have programs included or sold separately that you can install on other systems dedicated to 3D rendering. You build a "render farm" and those sub-systems are put on your local network. My network, as most high-end 3D artists consists of Cat 6e (NOT 5e) Ethernet and are hard wired connection for best speed and reliability. This means you can setup as many "render nodes" as you want with each one processing a rendering task. A simple way to think of it is something like "SETI at home" where they use your unused CPU cycles to make a large pool of processing power.
There is also another problem with using an Apple Mac computer and that is the fact of some 3D applications work better under Windows 7 64bit. The reason is that is where the majority of their user base is at and therefore more focused on fixing bugs on that platform. If the Mac version does get fixed, which may or may not, it can be months later. Also, some programs and plug-ins simply are not available on the Mac.
What this means for someone like myself is I am VERY dependent upon new hardware. Since Apple has left the Mac Pro behind with very late product cycles it makes it impossible for me to continue their support. The Macs I have now are relegated to server status for part of my render farm. At this time I have gone back to building my own custom computers and most likely will never go back. For family and others that do not work with programs like this, I would certainly recommend a Mac. But if you are really into 3D art design, then the choice is clear in my opinion.
This was long, but I hope it explains just what those high-end computers can and are used for.