Building a mini-ITX system that is small enough to be attached to the back of a monitor or hidden with your stereo components takes a bit more thought than assembling a full ATX system.  It is not just about the size of the components you are purchasing, heat dissipation is much more important in a small system especially if it will be located somewhere that does not have great air circulation.  TechSpot has put together a guide for those thinking of building such a system, using the Akasa Euler Case as the housing and powered with a Core i5-3470T.  As you can see from the picture below, the final system is smaller than an HD7970.

"The idea behind the Thin Mini-ITX form factor, besides the obvious which is to create seriously compact computers, is also to allow for DIY all-in-ones (think of little PCs you can attach to the back of your monitor). Having that said, we don't fully intend to go the all-in-one route in this article, but are aiming to build a powerful Thin Mini-ITX system that can be used in the office or at home as a media PC.

This is what our finished system should look like: extremely compact, powerful, and near silent operation, as in no-moving-parts silent. For less than $700 including a 256GB SSD, we believe you'll love what the final product will look like."

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