http://www.maketecheasier.com/differences-between-mbr-and-gpt/
ASUS k95VM
I found no support for this notebook (Original WIN7) on Asus Website for Win 8.1 ?
Using the hotfix removed the watermark, but some app did not work well.
Asus adivise was te empty hard disk en reinstall Windows on MBR iso GPT.
I bought an SSD and I first configured it to MBR.
Booting from the backup Windows 8 (64bit) disk, I installed Windows 8 pro with mediacenter & upgraded to Windows 8.1.
Now all is working perfectly.
Of course you need some skills to do all that yourself.