Trials of an Intel Quad Processor System: 4x E5-4650L from SuperMicro
DELL POWEREDGE R910 0KYD3D 4-CPU PROCESSOR MOTHERBOARD 0P658H - NO CPU NO RAM | eBay
Amazon.com: X99 Motherboard CPU Combo, LGA 2011-3 E5 2620 V3 CPU Motherboard Set Support 4 Channel DDR4 Memory, WiFi Module, Gigabit Network Card PC Motherboard for Desktop : Everything Else
Intel 4-way or 8-way MP motherboard (4 or more CPU) | Acmemicro
Boston - X11 Skylake 4-way Motherboard
Amazon.com: ASUS WS C621E Sage Extreme Power Intel® Xeon® Processor Workstation Motherboard for Two-way XEON CPU performance, with U.2, M.2 connectors, dual Gb LAN, USB 3.1 Type-C & Type-A, 10 x SATA
New, Supermicro, X10QBL-4CT, Quad socket Motherboard, Motherboard only | eBay