After I set the jumper J32 to 2-3 (x8/x8) on the X8SIU-F motherboard, when I set the SBX1 PCIe x16/x8 OpRom to disable and SBX1 PCIe x8 OpRom to enable, why the option ROM of the add-on card on the top slot still shows but the one on the bottom slot disappears?
This is a normal behavior. The SBX1 PCIe x16/x8 OpRom corresponds to the bottom slot, and the SBX1 PCIe x8 OpRom slot corresponds to the top slot.