In case I'm not the only one who wondered if the Core V71 would accommodate three 3-HDD cages, I'm excited to report it does! To do so of course I needed to get a third 3-HDD cage to swap with the top 2-HDD cage.  Then it was simple and easy: I removed the bracket for the lower optical drive bay (it was held on securely by only 4 easily accessible screws). Then I slid the third 3-HDD cage into place.  Only the lower (not the upper) pair of thumbscrews attaching the top 3-HDD