@krzychunh @Lost_N_BIOS
I don’t think he is being stopped by an ACPI issue (although the ASUS GL753VE does has ACPI issues when disabling Nvidia Optimus)
1. Windows 7’s native video driver (vga.sys) isn’t UEFI compatible (so as Lost_N_BIOS said) you must enable CSM and ensure Video is set to Legacy.
2. The ASUS GL753VE is a UEFI class 2 device (supporting UEFI+Legacy) however secure boot is configured by default from Asus and must be disabled and any security keys cleared (as Lost_N_BIOS said)
3. I don’t know if your model has a HDD or SSD but there are no drivers for NVme SSD’s in the Windows 7 boot.wim/install.wim by default so you will need to add them if using the stock Microsoft ISO.
4. The AHCI storage device for SATA drivers will also need a driver added to the boot.wim/install.wim (especially to install Windows 7 from the DVD drive)
5. You didn’t sate if you are using a USB stick but if you are it must be inserted into the USB 2.0 port on the right side as there are no USB 3.0 drivers in the Windows 7 boot.wim/install.wim by default
Wow, so many options! I was mainly looking to change PROCHOT temp, but it looks like I can learn a lot from these new opportunities. RAM clock modifcation especially seems interesting, though I can’t seem to reset CMOS by pressing power button a long time, so it is a bit dangerous.
Very grateful to you for your work!
FYI to others who come across this, my laptop is actually the cheaper FX73VE. It is basically the non-gamer GL753VE but with only cosmetic changes (monochromatic KB backlight, no ROG logo, no red “gamer” accents, no ROG key). Everything internally is the same, even the same BIOS, and ASUS lists the BIOS file on their FX73VE download center as “GL753VE BIOS”. I believe the same relationship occurs with the VD models.
@MrCocoNuat - Thanks for quick test and report back, glad to hear flash went in smoothly! 
There may be clear CMOS pads on the PCB, you’ll have to check around. It may look like one tiny gold circle, with fine split in the middle.
If you get stuck, try to remove one stick of memory and the HDD/SSD, sometimes that will reset CMOS, if not, you may need programmer to recover. So yes, be careful a bit