GPU Not Detected in Poweredge R620

Hello! I have been trying to install an Nvidia Quadro M4000 GPU in my PowerEdge R620 server. Since the motherboard only supplies 75 watts of power to the system, I purchased an external power supply to meet the card's 120-watt requirement.

However, when I start the system with the external power supply plugged in and connected to the GPU, the system does not detect it; it does not show up in the BIOS or the operating system. When I disconnect the external power supply from the GPU, the card appears in the BIOS and the OS, but I cannot get a signal from it, as it prompts me to connect the card to a power supply.

I installed the operating system using the integrated graphics, as suggested in other posts, but I am still unable to get any video output, even when the card is detected.

It would be super helpful if anyone knew what was wrong with the system or how I needed to do the process differently. Thank you for your time!

Here is a picture of the current setup for chuckles: