He has that and is looking to upgrade
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Bottom line is that there is nothing, TMK, mITX that is on the ESXi HCL.
There is also nothing I have found that supports VT-d and has a ESXi management network supported nic out of the box. The Intel DQ67EP is a great board and supports VT-d but the slot needs to be used for a nic for the ESXi management network. The S1200KP is an almost perfect ESXi board apart from the VT-d being, allegedly as I have not been able to test myself, disabled. The next best thing is the S1200BTS (MATX) or S1200BTL (ATX) boards but they are of course a bit bigger than you were looking for. They are however on the HCL but require ECC ram.
I an in the process of selling off my DQ67EP based setup to someone as I have moved to the S1200BTL for this exact reason. I guess you may be able to pass the two e-sata ports to a VM on the DQ67EP board and attach external e-sata das boxes for the drives but you are limited by the two e-sata connections so may get limited with more than two mechanical drives on each. Maybe a solution for home but not for the office. The
S1200BTS/BTL boards (pdf) also come as ready built bare bones in 1U rack or pedestal configs. The added advantage, especially for work is the ability to adjust and add more cards for storage attachment / networking / san in the future.
As an aside, the Fractal mini array is a nice case, have one of these, although with the one fan the area above the drive cage can get a bit hot. The Lian Li PC-Q25, Q18 and Q08 are also reasonable contenders.
RB