Here's a peak at the ASUS PRIME X299-A, this is an "entry-level" X299 motherboard from ASUS that will probably be priced around $200. More specifications at TPU.
Built in the ATX form-factor, the board draws power from 24-pin ATX, 8-pin EPS, and a 4-pin ATX power connector. It uses a simple 8-phase VRM to condition power for the CPU. The LGA2066 socket is wired to eight DDR4 DIMM slots, in addition to three PCI-Express 3.0 x16 slots (x16/x16/NC or x16/x8/x8). Two close-ended PCI-Express 3.0 x4 and an x1 slot make for the rest of the expansion.
It's too much to cover it all so here are links to the product reveals: