Can a PCIe NVME SSD be used in an slot?

The PEDET should be irrelevant It is pulled up by host and it selects between SATA and PCIe mode in Key M based on insertion of SATA or

2 SSDs use the PCIe interface, which allows for much faster data transfer rates than SATA SSDs, which are limited by the SATA interface SSDs can achieve

pcie x16 expansion slot 2 slot be used for? How is hardware mounted? PCIe or PCIe ? What is ? Recommended SSDs

pcie 40 in pcie 30 slot The slot can interface with SATA , PCI Express (the default