Looking for a beefy workstation board to host a couple of Haswell-EP processors? Gigabyte's MW70-3S0 might be just the ticket. This monster squeezes dual LGA-2011v3 sockets, 16 DIMM slots, six PCIe slots, and a boatload of storage into an Extended ATX form factor.
Although the board has a basic discrete graphics chip built in, you'll probably want to add a separate graphics card. Or three of them. Half of the PCIe slots offer 16 lanes of Gen3 connectivity, complete with support for two- and three-way CrossFire and SLI configurations. The remaining expansion slots use x8 connectors.
According to the manual, the board can take up to 512GB of RAM running at 2133 MT/s. 10 SATA 6Gbps ports are provided by the Intel C612 chipset, a close relative of the X99 chipset found on desktop boards. Gigabyte also adds an LSI SAS controller that supports up to eight 12Gbps devices via dual mini-SAS ports. I don't see any M.2 slots for mini SSDs, though.
Intel kicks in dual Gigabit Ethernet controllers, while Realtek supplies one of its ubiquitous audio codecs. If you want to bypass the onboard DAC, there's a digital S/PDIF audio out in the rear cluster. USB connectivity is limited to dual ports at the rear, plus two more via an internal header. And, speaking of headers, there are seven PWM connectors for CPU and system fans.