Let me see if I can help you with this.
You are correct the 660M did and apparently you have the 3D screen 1920/1080 screen was shiny and 3D
You should have 1 accessible Ram slot open, you need to match the Timings and voltage of the current RAM you have 16GB should be enough even for 3D Modeling, If you think you can use more you can have the internal RAM removed and Replaced, that requires dissemble of your notebook
The Most Noticeable upgrade you can make would be to Replace your OS hard drive with an
Samsung 860 Pro Even 2 of these? SSD will really cut your rendering time a lot. Even the older Samsung 850 Pro and or Evo will be Way Way faster than the hard drives you are currently running. Hold on to your hat faster.
For Greater storage of large files I see WD Now has a
4TB Passport external USB 3.0 drive,
I have to say here now the G75 left USB ports suck for USB hard Drives. the G7*** series all have a daughter card on that side and there are unsolvable issues. The Solution is to use the right side USB 3.0 Ports. I personally use a
right angle USB 3.0 Adapter cable and a
4 port Powered hub. Works well for me going on 5 years now.
You could download your Manual
Asus Support Downloads to better understand how the 3D works on your notebook. According to your list of spec you do have the 3D model.. Here is a link to an old thread concerning 3D on your model
https://rog.asus.com/forum/archive/index.php/t-25489.htmlThere is not much you can do with the GPU or CPU what you have is still good.
Your key board is getting old you might want to consider a Bluetooth Keyboard and Mouse Logitech seems to be the best.
Hope this is some help for you.
G752VY-DH72 Win 10 Pro
512 GB M.2 Samsung 960 Pro
1 TB Samsung 850 pro 2.5 format
980m GTX 4 GB
32GB DDR 4 Standard RAM
Z97 PRO WiFi I7 4790K
Windows 10 Pro
Z97 -A
Windows 10 Pro