It's basically a problem with your graphics card, so try doing this.
In the boot options go to graphics injector and make a tick on intel graphics injector.
Also make sure you go to your bios and disable your discrete graphics Card.
After doing these to things, it solved the issue for me!! Hope it helps!
I installed Yosemite with the use of iGPU but when I installed the eGPU as mentioned on the title the loading screen stuck on caution.
I also tried the bootflags such us nv_disable=1 and nvda_drv=1 also I tried GraphicsEnabler=Yes/No but still no luck. What might be the possible problem? Image link