MacPro 3.1 / 980 Ti - 4k image too small (switchResX?), no screen for recovery mode

[hoobastinker]

Just got a Geforce 980 Ti and 4k tv for my old MacPro 2008. 4k image is too small, and no controls for scaling, so trying to use SwitchResX, but it now says no custom anything in OSX 10.11.6 (can't update further) without first disabling SIP which seems to require CMD R at boot. Unfortunately, no screen comes up when I do this.



Is this because the 980Ti can't display the recovery mode boot screen? It is "mac flashed", and does display option boot for drive selection. Is something else going on, or am I going to need to reinstall the factory card just to access recovery mode just to disable SIP?



Am I missing another utility or simpler way I can get scaling options or other way to fix the display?

 

[nitromullet]

Have you installed the NVIDIA Mac OS X drivers for 10.11.6? If I recall correctly, you have to have the specific version of the driver written for the specific OS X release.

http://www.nvidia.com/download/driverResults.aspx/105589/en-us

Although, perhaps that only applies to the latest version. It is possible that the newer drivers are backwards compatible.