10GbE NIC in PCIe x1 , Will this cause problem?

Will PCIe x1 x4 cards work in x16 slot? x1 pcie slot SATA card for PCIe x1 slot with 8 ports Bizarro x16pciexp slot I tested PCIe x4 10Gbe NIC in a PCIe x1 slot, and here's my thoughts and results

x1 slot 1) First is simply looking at the motherboard, many times printed on the PCB near the PCIE slot is the actual X4 or X16 or whatever it happens