Motherboards Explained: The AAFP - Overclockers UK
To use a PCIe SSD, the motherboard must have available PCIe slots and, for M.2 PCIe SSDs, an M.2 slot that supports PCIe.
How to know if an M.2 SSD is compatible with your motherboard
Buying a compatible M.2 SSD for your PC can get confusing. Here's how to make sure your SSD is compatible with your motherboard.
Can I Use a PCIe 3.0 Card in a 2.0 Slot? - PC Guide 101
Just to clarify, if you have an Intel motherboard with M.2 Gen 5 and M.2 Gen 4 and choose to install your SSD into the M.2 Gen 4 slot, you will not lose any PCIe bandwidth for the graphics card.