Hey. I've searched the forum beforehand for the problems related to the 10xx series of Nvidia cards and First Generation Mac Pro and all of the advices don't work for me. Of course, I may have slipped some of the threads, but still, most of the problem solving issues end up in two-three actions with: drivers, power management and clean installing the OS. So here are my specs: Early 2009 Mac Pro 5,1 flashed from 4,1. 16 GB RAM. Kingston 240 GB SSD as bootdrive. El Capitan 10.11.6 (15G1611). 1060 6GB Nvidia GPU (8-pin power connector) and 1060 3GB (6-pin connector). Driver guide from MacVidCards. 8-pin connector coming from 2x6 mini connectors and the original 6-pin connectors from ATI. Stock GPU is ATI Radeon HD 4870 512 MB. I've done the steps from this post, triple checked, that the Nvidia drivers are set, and I end up having a black screen with no video output whatsoever after restart. Via screen sharing I see that the display is recognized as "pci10de, 10f1" in the Nvidia driver manager. The system information shows that the display resolution is at 1280 x 1024 and no further information. Although, "No Kext Loaded" is somewhat disturbing. I don't want both GPU's to run. It is just a coincidence that I have these GPU's that I can test and play with. I need only one of them to work properly. Spoiler: Screenshots What I have tried: Different versions of drivers post my build (15G1611) and pre my build (for the research sake and "what if"). Power is not an issue, since the 1060 both 3GB and 6GB work perfectly fine in the Bootcamp with the mini connectors and external PSU connectors. Resetting NVRAM and SMC (another "what if") Booting one of the two 1060's with the NVIDIA GeForce 7300 GT that I have from the even older Mac Pro 1,1 for the boot screen. The result is the same, as with the screen sharing. The only difference is that with the 7300 I can actually see the display, but not the working 1060's. The clean install did not help. Installed CUDA drivers. No difference. Did the combinations of different driver versions and installation and no installation of CUDA drivers as well. It takes time. But no effect at all. I would appreciate if any person could guide into any other way other than what was already tried and may be effective. I am really concerned with the No Kext Loaded. I am not a specialist in these kind of things. Thanks a lot in advance. Cheers.