The Shuttle DS81 ships with an H81 motherboard, an external 90 W power adapter and the 190 x 165 x 43mm case of course.  That means you have your choice of installed Linux or Windows and any combination of 65W or lower Haswell processor, memory and storage device to add to the ~$200 enclosure.  For outputs it provides HDMI and two DisplayPorts which means it can theoretically support 4K video, a pair of both USB 2.0 and 3.0 ports and two LAN ports as WiFi is optional.  While it has only headphone out for audio, the onboard codec is capable of outputting digital sound through DP or HDMI which would be the preference of many users.  Check out MadShrimps full review here.

"The Slim PC chassis from been reincarnated in the shape of the DS81 which supports the latest Haswell processors with a TDP up to 65W and supports 4K video output thanks to the DirectX 11.1 IGP. The DS81 chassis features a 1.3-liter slim design with a thickness of only 43mm, so it is suitable for many commercial applications; a VESA mount is also included as a bundle in order to mount the device behind the monitor."

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