Asus support Download You'll need the ATK drivers update all Chipset IRST IME. Your ram is probably not compatible Which ones did you put in??
See
Rewben thread on upgrading
For Ram you'll need 4 8GB sticks all the same and compatible with the G75 on the download site you'll see a list of compatible tested RAM. If you did use all 4 matching sticks try reseating them. Install only the under the keyboard Ram Stick first once you have them working then add the easy ones. If the first two aren't working you have an incompatibility or bad Ram.
If you tried to change out all that hardware in one shot it will be difficult do trouble shoot. I would suggest you put your old hard drives back in and then with an working OS then add Ram once that's working then add SSD with either a Clean Install of Windows 8.1.1 or Clone from your original hard drive and upgrade to Windows 8.1.
Get your updated drivers from the Window 8.1 section of the Asus Download, then go to the Windows 8 for the rest of the drivers. I think in the Win 8.1 section there is only Bluetooth and Wi-Fi drivers window 8 and windows 7 section will have all the rest you need.
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