graphics card not working

[TechFromHardgraves]

okay so i ran into a problem with my budget build, my hd 7850 isn't working with my dell optiplex 3020 board. now i tested the card in my main build and it works fine so its not the card, then i tested the optiplex board with a rx 560 works fine. so what is causing the hd 7850 not to work with the optiplex board?

[Tr1ggerfish1]

How many watts is your psu?

[TechFromHardgraves]

evga 500watt

[TechFromHardgraves]

actually its a msi 7870 2GB 

[Tr1ggerfish1]

2 minutes ago, TechFromHardgraves said:

actually its a msi 7870 2GB 

What exactly is the issue? Is it not being detected, No video output, Crashing.

[TechFromHardgraves]

so theres no display with the optiplex board but its works fine with my main pc