underscore with a3/b2 in corner

[maximusboy]

I just installed a new gpu and psu to a computer, the computer had worked fine until the upgrade. All thats been outputted is a underscore on the top left and a3 in the bottom right, after 30 seconds the a3 changes to b2.

 

[popatim]

Your pc may have defaulted back to using the integrated graphics as the primary output, if it has integrated. Try connecting the display to the motherbd port if you do.