CX450m and cable for video card confusion

[MrAOK12]

I tried to replace the videocard in my itx build and I can't get the video card (which is refurbished) to work and am trying to look for errors. (It probably is a bad video card, but I want to run through alternatives before I start paying to test the videocard)

I am trying to replace a Radeon 560 card (which doesn't need a power supply connection) with a Radeon 6500xt which does need a connection and on my Corsair CX450m semi-modular power supply I plugged one of the unused connection cords into the connection marked PCi-I on the power supply and then into the graphics card. 

The fan on the graphics card spins, but I get no video, not even a boot message.  (i neglected to remove the AMD adrenalin driver when I switched, but I'm going from one Radeon card to another and I should still see a boot message)

Did I do something wrong? is the power supply not sufficient for the video card? This computer has a Ryzen 3100 chip if that impacts anything. As I indicated, the computer works fine with the Radeon 560.

[Corsair Notepad]

Sounds like a bad GPU.