Tesla K10 multiGPU Windows 10 "Code 12 - not enough resources"

Hello, I just got my hands on two NVIDIA Tesla K10 GPUs that I wanted to put in my Tower. (Its a MacPro 5.1 running unsupported Bootcamp Win10 x64). Since the K10 is a dualGPU, the device manager shows 4 Tesla K10s. However, only one chip of each GPU works, the other one does not and always says “Code 12” in devicemanager. If I only install one K10, both chips can be used.

So far I’ve tried: different PCIE Slots, installing the official Nvidia driver (5 times, including older drivers), DDUing the old drivers, completely reinstalling the drivers for the Intel chipset and even resettet the PC, but nothing worked.

If you have any Idea on what I can try to get this working, please let me know, I am stuck with this issue for almost 4 days now. Thank you in advance!