Why would my MacBook Core 2 Duo boot only into safemode?

I purchased a Macbook Core 2 Duo second hand. Issue is that it only seems to boot into safe mode otherwise it loads then boots to a grey screen. When booting from a USB it will show a portion of the graphical installer but upon diving deeper to the install page it will boot into a grey screen again. I am honestly stumped as I have reset the PRAM, I have tried removing the battery and booting, Disk Utility and Onyx both say everything is fine. Could this be a dead GPU?