When you're thinking about gaming desktop, you're not just thinking about awesome gaming rigs capable of displaying the most realistic visuals out there, but a machine built with every specification to suit demanding applications. Gaming PCs are configured to run the best modern games today, but they can also be used to work in high-end applications which demand a lot of hardware power to run properly. You can use a gaming desktop for a whole array of tasks, ranging from video / audio editing, graphic design, 3D design or any other application which demands a lot from your system's hardware. With this in mind, think about all the benefits you can get from owning such a machine: not only can you game hard, with stunning visuals; you can also work a lot better since it will cut up loading times and improve your work-flow quite a bit.
Usually, such a desktop will incorporate a high-end CPU, with more than one built-in core. These are great for gaming, and are also great for multitasking when your job requires it. Since most applications rely heavily on the amount of information that can be processed, having a powerful processor by your side will improve the way you work by cutting the necessary time needed to get the job done by a decent percent.
You'll be able to run most applications with a quad-core without having to suffer from system halts or choppy operation.
Some of the new line of processors that recently hit the market has come out with the Hyper Threading technology built into them, which allows each separate core to take on two sets of instructions at once. What does this mean for you, the user? Well, in layman's terms, if your system is equipped with a quad-core with Hyper Threading technology, it will act just like an octo-core (just like having eight separate cores on your system).
The same line of new processors also incorporates the Turbo Boost technology which balances the processing power with the power consumption for a more "green" machine. When you need to run games or demanding apps, all cores will fire up to keep up with the application; but when the system is idle, the processor will step down to about 1600MHz to save power and deflate your monthly energy bill.
So having the central processing unit covered, it's time to move on to system memory. True gaming desktop will have plenty of RAM, since it's needed in large amounts for games to run smoothly. The lowest amount of RAM a gaming PC should be having nowadays is somewhere in the range of 4GB. Having this minimum amount will insure the application will run great without glitches or crashes. This is also great if you intend to use your gaming computer for something else rather than gaming.
Graphic designers, for instance will benefit from the added RAM to their systems, since they use applications which do demand a lot from a system, from processor to system memory. It's isn't unusual for them to run at least 2-4 applications at once, so the multitasking capabilities will come in handy.