If your computer is BIOS boot mode, but your system disk is a GPT disk. In this case, you cannot install Windows. However, you can convert GPT to MBR during Windows 7 installation.
Need to convert GPT to MBR during Windows 7 install? Let’s take a look at what are GPT and MBR first.
MBR (Master Boot Record) and GPT (GUID Partition Table) are two different partition styles. MBR is booted by BIOS, and GPT is booted by UEFI. MBR can only create 4 primary partitions or 3 primary partitions + 1 extended partition on the disk. And supports hard drives up to 2 TB. But GPT breaks this limitation and can create any number of hard disks on the hard disk, and supports hard disks larger than 2 TB.
According to the current situation, the trend of GPT replacing MBR is becoming more and more obvious. Microsoft even made a clear requirement that Windows 11 needs to be booted by UEFI if you want to upgrade from Windows 10 to Windows 11. In other words, your system disk must be a GPT disk.
Since GPT is better than MBR, why do we need to convert GPT to MBR? Before answering this question, I want to ask: when installing Windows on BIOS-based PCs using Windows Setup, have you receive the error message: “Windows cannot be installed to this disk. The selected disk is of the GPT partition style”?
In fact, some computer motherboards only support BIOS, not UEFI. So many users always use MBR disk and install Windows system on MBR disk. When your boot mode is BIOS, but the partition style of the disk is GPT, you cannot install Windows because the boot mode does not match the partition style. This is why you need to convert GPT to MBR during Windows 7 install.
When you install Windows 7, there are two ways to convert GPT to MBR.
Step 1. Open command prompt window during installation by pressing Shift + F10.
Step 2. Input “diskpart”, and then press “Enter” to enter the operating interface. Next, input “list disk” to check hard disk properties, and then press “Enter”.
Step 3. Now type “select disk 2”. By using this command, you select the disk number you need to convert to MBR.
Step 4. Input “clean” to clean up the current disk's partition, and then press Enter (This command will erase all data on the selected disk).
Step 5. Input “convert mbr” to convert GPT into MBR.
Step 6. When it completes, you can exit Diskpart and then go back to install Windows 7.
Warning: This method seems very concise. However, it has a big shortage, that is all data and files will be clean up. If you do not back up the GPT disk, then all the data on that disk are lost. If you do not want to lose all your valuable files, you can use method 2 to convert GPT disk to MBR without data loss.
AOMEI Partition Assistant Professional is a powerful GPT to MBR conversion tool. It can help you convert MBR/GPT to MBR/GPT without losing any data, and its operation is much simpler than Diskpart. Please download the Demo version for a free trial.
Before start, you should insert a CD or a USB flash drive to another working computer running Windows 11/10/8/7.
Step 1. Install and run AOMEI Partition Assistant Professional. Click “Tools” in the top toolbar, and choose “Make Bootable Media” and follow the wizard to finish creating a bootable media.
Step 2. Insert this bootable disk to the computer that you're having problem installing Windows on, and then choose CD-ROW Drive to boot from the bootable media.
Step 3. When the interface of AOMEI Partition Assistant Professional is loaded, right-click disk 1 and choose Convert to MBR.
Step 4. Click OK to make sure to convert GPT to MBR. At last, click Apply to save the operation.
AOMEI Partition Assistant Professional is a powerful software for partition management. It allows users to convert GPT to MBR during Windows 7 install without data loss and deleting partitions. Also, you can use it to convert FAT32 to NTFS without losing data, clone HDD to SSD and so on. Of course, if data loss is not an issue, you can convert GPT to MBR with Diskpart.