There are no RTX6000 "server" variants. These GPUs are designed for workstation use. I mean it is even in the name.

https://www.nvidia.com/en-us/data-center/rtx-pro-6000-blackw...

The workstation versions are fine if you're running one or maybe two cards with an airflow gap between them, but if you pack four of them right next to each other then you're going to have a bad time when the fans get going.