motherboard with 4 pcie slots: Asus ROG (X570) Crosshair VIII Impact, AMD, AM4, Ryzen 3000, (Mini ... . Wholesale Cheap Pcie X16 Compatible Graphics Cards - Buy in Bulk ... . Motherboard with 2 Graphic Card Slots - Durable & Efficient.
MotherBoard: ASRock B760M-C 1 PCIe 5.0 x16, 3 PCIe 4.0 x16 2 Hyper M.2 (PCIe Gen4 x4) 4 x DDR5
DIMM Slots (comes with 2 Memory Sticks).
In terms of I/O, the motherboard is equipped with three
PCIe x16 slots (1x Gen 5 x8, 2x Gen 4 x 4) and a total of four PCIe Gen 5.0 M.
2 slots.
To save yourself a lot of hassle with custom brackets, case modification and PCIe riser cables, you want a motherboard with either 7+ PCIe 3.0 full length
slots or at least 4
slots with dual/triple spacing between them.