I have bought two of the AMD Radeon RX5500 XT graphics cards, and the same thing happens with both. On both of them, the display ports will not work at all. None of the three. Even if those are the only ones that have anything plugged into them. I have verified it is not the cables or the monitors, because I have another machine with an older video card in which it support the multiple monitors. And to top that off, I have been using a 6450 and a 7450 on the same machine I am now using the RX5500 XT, and they supported multiple monitors. True they have HDMI, DVI, and VGA ports, but they worked.
My system is as below:
ASUS ROG Strix B550-f motherboard
AMD Ryzen 5 5600X processor
32 GB of DDR4 RAM
SSD hard drive
SATA Hard drives
AMD Radeon RX5500 XT graphics cards (8 GB GDDR6)
I would be very upset if someone states I have to purchase a different processor, because no where does it say you have to have a "G" processor to get the graphics card to work properly.