MSI's motherboard lineup based on the Z97 Express chipset is branched primarily into two lines, Gaming Series, and OC Series. The Gaming Series covers price points all the way from $100 to $220, offering a feature-set that's tuned for gaming PC builds with moderate CPU/memory overclocks. The OC Series, on the other hand, is ranged between $200 and $400, offering products tuned toward serious to professional (competitive) overclockers. The OC Series consists of three models, beginning with the Z97 MPower, the Z97 MPower MAX AC, and the Z97 XPower AC.
The Z97 XPower AC is MSI's flagship motherboard, which is designed for builds with not just strong CPU and memory overclocks, but also 3-way and 4-way multi-GPU overclocks. It features a PEX8747 bridge chip from PLX, which lets it drive four PCI-Express 3.0 x16 slots, and an overriding single PCI-Express 3.0 x16, which when populated, wires the add-on card directly to the CPU's root complex, bypassing the bridge chip. The CPU is powered by a 16-phase VRM that draws power from a combination of 8-pin EPS and 4-pin CPU power connectors. Other electrical inputs include 24-pin ATX and 6-pin PCIe, to stabilize power delivery to the add-on cards. Connectivity on the Z97 XPower AC includes ten SATA 6 Gb/s, an M.2 slot, twelve USB 3.0 ports, AudioBoost audio with in-built headphones amp, 802.11 ac WLAN, Bluetooth 4.0, and gigabit Ethernet, driven by an Intel-made controller. It features a boat load of OC friendly features, including a coolant channel for water-cooling the CPU VRM, voltage measurement points, onboard OC/voltage fine-tuning buttons, and redundant BIOS.
The Z97 MPower MAX AC is a notch below the Z97 XPower AC. It offers a milder 12-phase VRM to power the CPU, but one that draws power from a combination of 8-pin EPS and 4-pin CPU power connectors, and featuring a coolant channel through the VRM heatsinks. There's no PCIe bridge chip, but the board still offers three PCIe 3.0 x16 slots (x8/x4/x4 when all three are populated). Storage connectivity on this board includes eight SATA 6 Gb/s, and one M.2 slot. The rest of its connectivity includes ten USB 3.0 ports, 802.11 ac WLAN, Bluetooth 4.0, gigabit Ethernet, and AudioBoost audio with headphones amp and ground-layer isolation. The Z97 MPower MAX is the most "affordable" of the lot, at under $200. Its feature-set is more or less identical to that of the Z97 MPower MAX AC, except it lacks 802.11 ac WLAN, Bluetooth 4.0, liquid-cooled VRM heatsinks, and onboard OC fine-tuning buttons.