Here is the spec for the T7610 from the Dell manual, it doesn't relate to the "CTO Base".
Discrete (PCIe 3.0/2.0 x16)
T7610
up to 4 full-height, full length (maximum of 600 W)
This suggests you can use many different video cards. . You say "display ports". What are you referring to? "DVI", "VGA" or the actual newer Display port interface?
Dell also has a support forum, staffed by mostly users like this forum. That is another alternative for specific Dell hardware help.
Desktop - Dell Community