What happens if you use a PCIe NVMe SSD in a PCIe

PCIe 4 NVMe drive in a PCIe 3 slot m2 pcie 4 0 in 3 0 slot Pretty much as the title of this review says This card slots into a PCIe x1 slot, and thus forces any NVMe SSD to run at those speeds--with a max m2 slot mainboard Also I'm wondering for eGPU's I have found to physical 16x pcie slot adapter and I'm assuming hardware will show up in due time I

m2_1 slot You can plug pcie into slots as it's backwards compatible but the speeds will be limited to Gen 3 It wouldn't be able to go above the