its probably the lcd ribbon.
you can easily buy one off ebay for few bucks and replace it yourself but you would have to take half of your laptop apart including your display in order to replace it
while its not hard and a monkey could do it its pretty tedious and long process (I know because i did it myself)
Asus Rog G750JZ
Screen: 1920x1080 17.3'
CPU: Intel® Core™ i7-4700HQ (3.4Ghz @ -70mV)
GPU: GeForce GTX 880M 4GB (OC +125Mhz Core, +600Mhz Memory @ 1.062V)
RAM: Samsung 32GB 1600MHz
Storage #1: Samsung Evo 840 250GB
Storage #2: Samsung Evo 850 500GB
Storage #3: Seagate Barracuda 2TB
Storage #4: Samsung Evo 128GB MicroSD