same thing happened to me, read my thread, exact same symptomps, this laptop dies suddenly it seems
i took it to the service center
they said the motherboard, SSD, and HDD got fried and they need to replace them:
http://rog.asus.com/forum/showthread.php?43397-G750JX-black-screen-pls-help&country=&status=PS:
Which OS did you have installed? 8, 8.1, or 7?
What was your BIOS version? 209? seems like it is a buggy BIOS
ASUS G750JX-CV050HCPU: i7-4700HQ @ 2.40 GHz.Memory: 32 GB DDR3 1600 MHz. Hynix RAMGraphics: GeForce GTX 770M 3 GB GDDR5 RAMStorage: 256 GB LiteOn LCM-256M3S SSD + 1 TB Seagate Momentus ST1000LM024 5400 RPM HDDScreen: 17.3" Full HD 3D Glossy ScreenRouter: ASUS RT-AC68UOS: Windows 7 Professional (x64)Security: Webroot SecureAnywhere Antivirus for PC Gamers