PCIe x8 Gen3

The QNAP one looks like it is x4 so I would need a ribbon cable and find a way to mount without fitting it in the x1 slot

Yes, you can use a PCIe graphics card in a PCIe slot PCIe slots are backward compatible with PCIe cards, meaning they can still work together

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pcie 20 x16 slot Thank you for posting in Intel Ethernet Communities The Intel Ethernet Network Adapter I225-T1's System Interface Type is PCIe In