iMac late 2013 27" problem with display resolution

[SViK Pro]

Hello,

I have a problem after updating my iMac 27" late 2013 (NVIDIA GeForce GT 755M 1024 MB) to macOs Sierra. I cannot set the standard resulution of 2560x1440. If I select Display prefs it shows me <cannot remember>x720 and nothing more. When I press option key I see additionally 800x600. I have resetted nvram but after the reboot I see snow on display before the loging screen appear.

Can you help please?

Vladimir

 

[SViK Pro]

Hello,

I have made a diagnostic and got two errors: VFD004 and VFD005. Seems that graphic card problem. But I never heard about such a behaivor. Sad. Does anyone have such a problem and maybe price to repair?

Thanks
Vladimir

 

[Fishrrman]

Was it working properly in 10.11.6 (El Capitan)?
If so, go back to using that...