The MSI X99S GAMING 9 ACK is an Intel X99 (LGA2011-3) E-ATX gaming motherboard designed for Intel Core i7 Extreme Edition and Xeon E5 v3 processors. It features an 8-phase digital power design with Military Class 4 components for stable overclocking, supporting Quad Channel DDR4 memory with XMP profiles up to 2133MHz across 8 DIMM slots (max 128GB). The board provides 5x PCIe 3.0 x16 slots (x16/x16/x8/x16/x8) for multi-GPU setups with SLI/CrossFire support, plus 1x PCIe 2.0 x1 slot. Storage includes 10x SATA 6Gbps ports (8x from X99 + 2x from ASMedia controller) with RAID 0/1/5/10 support, and 1x M.2 PCIe 2.0 x4 slot (32Gbps). Networking features dual-band 802.11ac WiFi and Killer E2205 Gigabit LAN with advanced traffic optimization. Audio is powered by the Creative Sound Core3D quad-core processor with 600Ω headphone amp and gold-plated audio jacks. Additional highlights include USB 3.0 ports (6 rear + 4 via header), MSI Gaming Device Port for reduced input lag, V-Check points for voltage monitoring, and Mystic Light RGB lighting with 16.8 million color options. The board also features multiple temperature sensors, BIOS Flashback+, and an onboard power/reset button for benchtop testing.