Asus Motherboard, SUPPORT FOR 4-WAY NVIDIA SLI AMD CROSSFIREX (WS X299 SAGE/10G)
Z390 GAMING SLI (rev. 1.0) Key Features | Motherboard - GIGABYTE Global
ASUS Introduces World's First AMD Motherboard Supporting SLI Dual-PCI Express Architecture – Hartware
MSI Z370 SLI Plus
SLI requires motherboard support in order to work, meaning you need multiple pcie slots AND SLI support within the bios itself. If one were to connect a dual gpu card, such as