Question PCIe Gen 3 M.2

Jun 7, 2022
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On my MSI MPG B550 Gaming Plus, it has a spot for M.2 PCIe gen 4 and gen 3. I just got my first M.2 gen 3 so I’m very new to this. Can I put my Gen 3 into the gen 4 slot since it has a shield for better thermals? Or do I have to put it in the PCIe gen 3 slot?