Which one of the PCI-E 16X slots is it in? top or bottom?
Out of the 3.0 ports it's in the bottom one.
Out of all the 16X ports (2x 3.0, 1x 2.0) it'd be the middle one.
- 2 x PCI Express 3.0 x16 slots (PCIE2/PCIE4: single at x16 or dual at x8/x8 mode)