motherboard with many pcie slots
PCI Express - Wikipedia
Asus announces B250 Mining Expert motherboard with 19 PCIe slots and triple 24-pin power connectors.
HP Z2 G4 motherboard question about M.2 slots
Buy MACHINIST X99 LGA 2011-V3 Motherboard, Micro ATX Motherboard (PCIe 3.0, M.2 Slots, 4 Channel DDR4, SATA 6Gb/s) for Intel XEON E5 V3/V4, Core i7 seriers ...
What generation are the NVMe slots? – Q&A – Best Buy
Dual M.2: This ATX motherboard is equipped with flash NVME M.2 (PCIe 3.0 X4 bandwidth) and AHCI M.2 (SATA 6Gbps) slots, of which NVME M.2 maximum speed Up to 32Gbps.