Amazon.com: SHANGZHAOYUAN X99 Dual CPU Motherboard LGA 2011-3 Server Motherboard for Intel i7 5th/6th Gen Xeon E5 V3/V4 Series (E-ATX, 8*DDR4 ECC Max 256G, 2*NVME M.2, 2*Gb LAN, SATA 6Gb/s, PCIe 3.0) :
ASUS Prime B450M-A II AM4 Micro-ATX Motherboard PRIME B450M-A II
Building a Dual-CPU Behemoth from Used Server Parts, ft. CaseLabs & Old Xeons - YouTube
Amazon.com: AMD A320 M ATX Gaming Motherboard, Support AMD AM4 Socket a Series APU and AMD Ryzen CPU ATX Motherboard (4 SATAIII Port, M.2 Port, Graphics Card Slot, 2 DDR4 Memory Slots,
Best Buy: EVGA Classified SR-X Desktop Motherboard Classified SR-X