Hi my friends,
Just to save you some time here! My dream is over...
Was going down the Nvidia road on a late 2009 27"Core 2 Duo system using the web-drivers for gtx660m2gb - replacing a 256 MB ATI card.
Well... it was kind of working, nice fast clock speed. Download the latest Nvidia drivers before you change your card. Thanks Jason for that tip!
It boots... but thats it for good news. No 2nd monitor available via cdmi using miniDisplay port, no brightness control on the main screen either. It does boosts the energy consumption of the system to double. It's getting hot in here! Also lost my e-SATA connection to a 2nd external hard drive... aaargggg.
The worst thing was after updating to Sierra the "new" system starts with the OS-X GPU drivers by default. Which leaves your in unsupported GPU in the dark so you don't have a working screen whatsoever. Have fun working with a black screen and no means to access a 2nd screen.
So for me this is a dead end my sport friends. Without a proper firmware code on your GPU & system, this is a no go! Quite a pity.
I wanted to render stuff on this machine. If somebody needs a working Nvidia GTX 660m/2gb- or has a working one pulled from a iMac card 2gb+ please let me know.
Cheers my brave friends, m