Dell 6 pin is effectively 8 pin because all three 12V pins are wired in this psu.  you can use a Dell straight 6 to 8 pin adapter cable for RTX 4000.  [URL] this is a very commonly used adapter cable in Dell factory.  my XPS has this to power a HD4870x2 while my Dell psu has 6 pins only.
I purchased an Optiplex 7070 (The fat tower one). It came with a small AMD RX550 GPU. The department this was setup for neglected to tell me that the software they are using requires an Nvidia GPU. I happen to have a Nvidia Quadro RTX 4000 in inventory. Is it at all possible for me to put this card into the 7070? What PSU will I need to make this work? Really trying to avoid having to purchase a different PC.
Optiplex 7070 Tower GPU Upgrade