Mac Pro 5.1 will not display image when upgrading GPU

Hi everyone,

I decided to upgrade my Mac 5.1 mid 2010 to a metal supported GPU but having problems getting an image on the display.

I first tried to upgrade to RX580, when i turned on the computer it chimed twice but no image on the display. It may have been a faulty cable so I changed it but still the same problem.

Tried a few solutions that i read online but nothing worked. So i returned the RX580 as i thought it was a faulty card.

I then purchased Radeon Pro WX7100, after installing it, i ran into the same problem. Computer chimes twice then keeps on running but no image on the 27 inch Apple Cinema display.

I would very much appreciate if anyone has any answers.

Thanks