Well I think window 10 will need to run UEFI, and that seems to be the issue. UEFI and BIOS won't mix for a bootable disk. Your OS 10 Should be UEFI GPT! Data drives don't matter. USB Install media seems to me much faster and more reliable as DVD are so sensitive to scratches etc.
If you want to continue with Window 10 preview I would suggest that your go to the
Windows 10 Forum there is excellent tutorial for installing and working around the issues and knowing when update versions come out.
All Your hardware drivers wil be found here
Asus Support Downloads If your going with 10 download the win 8 driver that are not upgraded to 8.1 so download the 8.1 driver first then fill in what's missing from the win 8 downloads.
I think Win 7 sp1 that originally came with the G75VW was set up UEFI but a lot of people not understand how to work with UEFI reinstalled BIOS MBR
Win 8 and 10 just work better UEFI I'm not sure that 10 even has a MBR version
So is you want to go back with Win 8 I suggest you check out the
Windows 8 Forum We have this thread that was put together from multiple threads back in 2012 and 2013 were we all worked through installing window 8 and 7 its a bit to read but very well put together by Rewben and solves all the issues of UEFI and installing Win 7 UEFI and Window 8 UEFI and MBR.
one other thing when your booting from either USB or DVD, hit th power button and ESC button that will bring up a boot menu from there you would Select UEFI UBS Or UEFI DVD for UEFI or USB or DVD for MBR once you get th install started enter language and then hit F10 this will bring up Command prompt from that command prompt run Diskpart
C:\> Diskpart
DISKPART> list disk
DISKPART> select disk (id)
DISKPART> clean
DISKPART> convert mbr (or gpt)
exit and continue the windows install
Another tip remove any drives besides the hard drive/SSD you are installing window on. once your installed and booting good then you can put your DATA drive back in. then on the next boot up use the F10 routine and select your Current C:\ drive to boot from.
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