Question BIOS and Mobo GPU compatibility

[CatFromBelow]

So I recently got an Alienware Aurora R3 from a garage sale everything works great except the graphics is very out of date.

I'd like to change to my Radeon RX 580 from my Radeon HD 6950 but when I install the 580 my motherboard doesnt recognize it.

Is there a solution to this?

 

[egda23]

Correctly connected the PCIe power connector from the PSU ?
What PSU is this this (power ?)

 

[CatFromBelow]

Correctly connected the PCIe power connector from the PSU ?
What PSU is this this (power ?)

I'm not sure of the PSU model but it's up to 1000w