I am using the X11DDW-NT motherboard with a single CPU. I installed two add on cards on the RSC-R1UW-2E16 riser card, but only one of the add on cards is detected. What is the issue?
Each of the PCI-E slots on RSC-R1UW-2E16 is from one CPU. With only one CPU installed , only one of the slots will work. You can use RSC-W-88 which can provide two PCI-E x8 slots from CPU1.