Display sleeps while installing opencore..

I have Success fully created the usb and it works absolutely fine. I get the apple logo then the macUtilities. Then I select install and it starts... But after few minutes the display turns off but the system is on.... Fans spin ,keyboard lights up

I am installing High Sierra on core 2 duo e7200 GPU inno3d gt 710 2 gb ddr3 Ram 4gb

Please help.