If you have another partition on the drive it must be erased. In that case, you need to make sure that all of the partitions on the drive have been erased.

bascically it doesnt install, in the current partition. and gives the same above mentioned erroe. it proceeds til the point til we can see the partitions. but when i boot into uefi boot, and select the usb. Hey, pinhedd, i did make the bootable usb in fat32 format using the rufus software. Now i hav main C drive of win7 and two disks of unallocated memory :-O but GPT option doesn't get highlighted at all :-( ? what shud i do? i deleted partitions from dskmanager. This is the error msg i get when i tried installing windows 8.1 64bit from a bootable USB. Windows can not be installed to this disk the selected disk has an MBR partition table on EFI systems, windows can only be installed to GPT disk. If all the partitions on the drive are deleted the installer should automatically convert it to a GPT format disk when the installation begins. Then, reboot and select the USB drive as the boot target. Set the partitioning scheme to GPT for UEFI computers, the file system to FAT32, and use the Windows 8.1 ISO as the source image. Instead, I recommend using Rufus () to create the USB installer from a Windows installation ISO. Installing from a bootable DVD does not present the same challenge. If the Windows installer boots from the USB in MBR mode it will not be able to properly install itself in GPT mode.

By default the Windows USB installer creation tool will not change the partitioning scheme or file system of the USB device itself. Installing Windows from a USB is a little bit problematic. For compatibility with BIOS based peripherals and operating systems, UEFI firmware can also read the MBR partitioning scheme. GPT is only recognized by EFI/UEFI based firmware. GPT is a new partitioning scheme designed to replace the MBR partitioning scheme and alleviate many of the constraints of the old format. It has been used for over 30 years and is tightly integrated with BIOS based firmware. MBR is an old partitioning scheme used for harddrives.

Gpt iso