This is just my guess, nothing concrete. Just speculation.
This is because Skylake no longer has FIVR.
http://www.anandtech.com/show/9483/intel-skylake-review-6700k-6600k-ddr4-ddr3-ipc-6th-generation/3
Due to the difference in power delivery for Skylake, I don't think current X99 boards and socket can support Skylake-E (when its out). Definitely need new board.
This is because Skylake no longer has FIVR.
http://www.anandtech.com/show/9483/intel-skylake-review-6700k-6600k-ddr4-ddr3-ipc-6th-generation/3
Due to the difference in power delivery for Skylake, I don't think current X99 boards and socket can support Skylake-E (when its out). Definitely need new board.


