Monitors won't display anything after installing new graphics card

[TOG_WAS_HERE]

Hi everyone,

I need some help here...

I am upgrading my Graphics card from a GTX 650 to an ASUS Strix AMD Rx 480... When I turned on my PC I got no display not even the BIOS/UEFI. The card lights up and all three fans spin up (At low RPM) at this point I thought it was either my new GPU or my Mobo not working correctly. So I install my old GPU into the same PCI x16 slot and works just fine. Bios comes up and boots into windows... Then I figure It's the new GPU. I put it into another PCI x16 I have and plug it in with the old GPU still in. It does not show anything again. However when I remove the power from the new GPU and keep it plugged into the PCIx 16 and keep the old one plugged into the power supply while in the PCI x16 as well it starts up just fine and the new GPU shows up in the Device manager... So nothing is wrong with the motherboard or the new GPU... At this point I installed the drivers from the disk and then updated through AMDs the gpus website. But still, when the new GPU is plugged into the power supply (I am using 8-pin and have also just tried 6-pin) I get nothing...

My specs are:

• 
  Windows 10 64-bit
  X79-UP4 GIGABYTE Motherboard
  i7 Processor 4th gen
  16 GB RAM
  2TB 7200 RPM HDD
  800W Power Supply

Other info:

• 
  I do not have integrated graphics
  I have tried disabling the old GTX 650 in device manager

Not sure what is going on, been trying to fix it for about a whole day so far.

Thanks!

 

[cwli1_]

What is your power-supply model? What is your old GPU?