So the difference being ACK as in AC and K. AC of course refers to AC WIFI, and the K is for KillerNIC Ethernet. This gorgeous motherboard has massive SLI/Crossfire support, AC WIFI, heaps of SATA3 connectors, M.2., overclock features and a nice audio solution.

The Gaming series really is supposed to be the mainstream model but I'd tag this is enthusiast class, alright. This MSI X99S Gaming 9 ACK will come with nice PC options like 8-pin EPS connectors, a 7+2-phase VRM design for the processor and memory, five PCI-Express x16 slots .

There is an extra EMI shield that covers the rear-panel I/O on-board, and audio is shielded as well. The board comes with a Killer E2205 gigabit NIC and 802.11 AC WLAN. Storage wise you will get ten SATA 6 Gb/s and of course an M.2 slot (PXie x4 linked this HEAPS of bandwidth). Overclocking features include voltage measurement points, and a diagnostic POST LED display.

Other keywords for this product are V-Check Points 2, OC Engine, Military Class IV components, SATA Express and M.2 interface and intricate Audio Boost 2 technology. The 9-Series gaming series is merged under that large Dragon/Dragoon style Gaming G-Series heatsink. Interesting is the inclusion of a  AverMedia Capture Card, it can stream gaming activities at 1080p 60Mbps without impacting FPS and gameplay.

Check out the MSI X99S Gaming 9 AC review right here.