So, I am trying to crossfire the SAPPHIRE HD5750 and SAPPHIRE HD6790. I got a GIGABYTE GA-P55-UD3R motherboard with a PCI-E x16 and a PCI-E x4. I installed the latest catalyst version as well as the drivers for both cards. I have the HD5750 connected to the PCI-E x4 and the HD6790 to the PCI-E x16 slot. I connected them with the crossfire bridge but when I open the catalyst control center there is no tab to enable crossfire. I checked with GPU-Z and both cards are clickable but the crossfire status is disabled. What should I do? Thank you in advance.