I assume you mean PCIe 1x videocard?
There's no way to disable the onboard video. Your best bet is to try all (both) PCIe slots in the server and see if any (either) works for the card.
Check if the OS sees the 2nd videocard (install drivers if needed) and enable dual monitor. Then switch the primary and secondary.
One note: the system will use the onboard as the primary videocard at all times most likely, so if you ever need to work in the bios, you may need to move your monitor/kvm to the integrated videocard temporarily at that time (unless you have a DRAC, in which case it wouldn't matter).
Member since 2003