You may not have heard of AVADirect as they are a medium-sized custom PC builder based out of a little town known as Cleveland, Ohio. Compared to a company like Alienware or Voodoo, AVADirect is much more centered on using off-the-shelf parts and designs to build reasonably priced alternatives that don't use custom expensive cases and other components. That means that, yes, you could buy this exact system yourself with a trip to your favorite e-tailer but with a pre-built system you get a guarantee and some piece of mind with already-tested components and a warrantee to boot.
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Review: PC Perspective