Server not starting, after adding graphisc card

Question

First of all, I want to clarify, that I pretty new to server topics. My server runs on normal ubuntu.

I bought a Nvidia Quadro k4000.

1. I built it into the server and connected the PCIe Power cable. - System health LED red

2. I plugged out the PCIe power cable - Starts up, and the screen tells me to power down and plug in the cable

3. I plug in the cable. -Return to step 1

What I tried:

1. Check if it is plugged in correctly
2. Try another cable
3. run the system again without the card. - works on its own

Please help me.