I installed RSC-R2UU-U2E4E8G riser card on X9SPU-F, but the 2nd slot cannot detect the card. Does it require to change jumper or BIOS settings?
RSC-R2UU-U2E4E8G is not fully supported on X9SPU-F.
X9SPU-F has one x16 (or x8+x8) signals and one x4 signals, so the maximum total outputs are three signals (x8+x8+x4).
Mechanically it can fit into 2U chassis, but it can only get three signals due to HW limitation on this MB.