Got an MSI X299 Xpower Gaming AC board but only had time to take some quick pictures so far. 1x 8-pin + 1x 4-pin. Not looking great, most plastic board yet.
VRM heatsink, plastic cover on top restricting heat dissipation. Most likely 12+1 phase configuration (6x2+1). Best guess for power stage would be IR3555.
Back of the VRM heatsink. Very thin bottom metal plate contacting to the heatpipe.
The heatsink by the I/O cover which connects to the heatpipe. Half of it is covered by the plastic I/O cover which really limits how much heat it can dissipate.
6x doubler ICs. No backplate.