Hello, we see you are looking for assistance. Click our DELL-Cares username, on the right click, "Send this user a private message". Provide to us the private Dell PC Service Tag. Update= Resolved-have found out my system does support two 4k monitors and it is now working.  Dell Systems Supporting HBR3 Specifications  
I have a Dell Latitude 5320 running an I5 processor. Will it support two 4k monitors?  Update= Resolved-have found out my system does support two 4k monitors and it is now working. 
Dell 5320 and dual 4k monitors