Browsing around some of the booths at Computex 2014 I spotted several X99-based motherboards, which are primed to support Intel's upcoming range of Haswell-E enthusiast CPUs. The X99 chipset supports four-channel DDR4, which is implemented in all of these boards, as well as other top-end features.
The first X99 board I spotted was at MSI's booth (pictured above), although the particular model they were showing was a pre-production prototype that is unfinished. You'll note two banks of four DDR4 slots, equalling two DIMMs per DDR4 channel, as well as 12 USB 3.0 ports, eight SATA 6 Gb/s ports, a SATA Express port and an M.2 slot.
Over at ASRock's booth the company was displaying two X99 motherboards, one of which was a functional model that we saw earlier over at Adata's DDR4 live demonstration. Specs of both motherboards are similar to MSI's model, such as ten SATA 6 Gb/s ports, ten USB 3.0 ports, an M.2 slot, and apparently Thunderbolt as well, although no SATA Express.
At EVGA's private suite they also had an X99 board on show, although like others it was pre-production. EVGA wasn't displaying specifications for their early Haswell-E-supporting mobo, but you can expect similar features to what I mentioned above.
According to more than one executive I spoke to from several companies, they're expecting to bring their X99 boards to market in September. Intel hasn't officially disclosed when Haswell-E and X99 will launch, but it's looking like it'll be September at this stage.