New GPU computer won't boot

[Publiano]

I switched from a Gtx 760 to an RX 480.

The fans on the card turn on, computer starts, but there's no signal to the monitor. It doesn't boot.

I had to buy a 6pin to 8pin adaptor for the 480. It connects to a two 6pin cable.

It'll boot when I swap in the 760.

The PSU is rated for 460 watts.

My system is some old XPS running an i7 2600. I don't know what the mobo is, but it only has one pci e slot.

I uninstalled all the Nvidia drivers and replaced them with the AMD ones.

It still doesn't work.. I don't know what's going on.

http://imgur.com/Bc5ca8Y

 

[decentgamer]

Did you plug the display cable ( could be DVI, HDMI, VGA, Display port,... ) to the RX 480? Don't plug it in the motherboard, it won't work as dual graphics ( onboard + GPU ) like laptops.

 

[atljsf]

sounds like your psu is not cooperating or the converter is not cooperating, time to get a new psu