Can I install PCIe x8 expansion card in a PCIe x4 slot on a QNAP NAS ?
Applicable Products:
Yes, the PCIe x8 expansion card (for example: QXG-10G2SF-CX4) can be installed in a PCIe x4 slot on a QNAP NAS, although the PCIe connection on the card is PCIe x8, bigger than the motherboard slot, it is still possible to connect and use it without hardware problem.

No blocking on the PCIe slot could avoid the connection to the expansion card.
For further assistance, ask other users and QNAP experts in the community. Go to QNAP Community