Without that requirement, you could definitely build an mitx system that smoked a NUC for same or cheaper (the 4590 I was looking at has a 7242 passmark). My requirements also called for a motherboard with vPro which drastically cut down selection and increased price. It's quite a bit bigger but still pretty small and had a much faster proc and dual NICs. A DIY system built around a mitx board and an Antec ISK110 was just a hair higher than a NUC when you add the RAM and storage to the NUC. However I recently was comparing a NUC to a DIY system for my home lab. So 2 streams would be fine, 3 maybe if 720p. The i7-5557U which comes in the NUC I mentioned has 4760 passmark score. Very roughly speaking, for a single full-transcode of a video, the following PassMark scores are a good guideline for a requirement: