I made a ocpl big sur installer and the EFI on a flash drive before I took the computer apart just in case. Will that work to overwrite the current operating system? witch right now is Sonoma . Thanks again for the help I’m pretty new to all this and enjoy learning about it.
I guess the OCLP installer you created on your iMac automatically, adhered to the stock GPU.
If that was the case then it might not boot properly with the Quadro card.
You will have use OCLP to generate the OCLP EFI again, manually.
Carefully read through each option (the tick boxe) on the OCLP menu, you will know which to choose and which not to.