[Solved] GeForce GTX 770 (2GB) No longer works

Good morning everyone,
I assembled my hackintosh about 4 years ago (OS: Mavericks, Hardware as in signature) until yesterday everything worked perfectly when this happens:

at the boot locks at the logo screen (grey apple with spinning circle)
the OS is loaded and is functioning in fact I can turn off the computer by clicking the mouse on the apple and choosing shut down using the cursor keys

at the moment I connected the monitor to the graphics card of the MOBO and after a snow screen displays the desktop.

Under windows and ubuntu graphics card works perfectly

How can I figure out what it is that does not work?

I'd check this thread for solutions?

https://www.tonymacx86.com/threads/...-direct-update-to-sierra.212826/#post-1419892

Thank you and excuse the delay.
After several attempts, I found that the graphics card to be broken!

Now the problem is that I have to replace it but they are not longer in business !!

Any suggestions?