Here’s how to install Windows 10 Technical Preview over current operating system (Windows 7, 8 or 8.1) so that can select which system to boot up on machine start-up (Dual Booting).
Before start, make sure that you have at least 20GB of free space on internal hard drive and a 4GB USB flash drive.
Stage One-> Download required software and files
1. Download Windows 10 preview ISO file. Link
2. Next, download and install the Windows 7 USB/DVD Download Tool. Link
Note: this software will help you create a bootable flash drive to install Windows 10.
Stage Two-> Prepare a bootable flash drive
3. Insert a USB Flash drive into PC. And then launch Windows 7 USB/DVD Download Tool.
4. Select the ISO file by clicking Browse button and click Next.
5. Choose USB device by click the USB device button.
6. Select the USB drive inserted to PC and then click Begin copying button.
7. Click Erase USB Device and click OK to confirm if prompted. The tool will then take a few minutes to copy files to the USB drive to create bootable USB drive.
Stage Three-> Prepare your computer
8. Next, go to the desktop control panel > Administrative tools > Computer Management > Storage and then select Disk Management to navigate to the disk management tool on PC.
9. Right click on C Drive and select Shrink Volume in the bottom window pane.
10. Enter the amount to shrink (min 20GB), which will be the size for Windows 10 drive. Click Shrink to allocated space of PC hard drive.
Stage Four-> Install Windows
11. Reboot the PC. Press F12 as soon as the system reboots in order to select your boot device. Select USB drive and press Enter
12. In Windows setup, click Next and follow onscreen to install Windows 10.
13. Select the partition that created which marked as “unallocated space” and click Next.
Note: Windows will take a few minutes to copy files.
14. Once finished copying files, system will reboot and display a boot menu.
Stage Five-> Finalize Windows Install
15. After PC reboot, in boot menu select Windows Technical Preview. It will copy more files and then reboot again.
16. Select Windows Technical Preview a second time, after the system reboot.
17. In express settings, click “Use express settings.
18. Sign in to Microsoft account or create a new account.
19. Verify account by entering the email address and then key in the code that received from Microsoft emails.
20. Select “Set this up as a new PC instead” so that can default install of Windows 10. Click Next to enable OneDrive.
Windows will take a few minutes to finalize your settings. Windows will present with the same boot menu and given the choice of existing Windows or Windows 10 Technical Preview.
7. Click Erase USB Device and click OK to confirm if prompted. The tool will then take a few minutes to copy files to the USB drive to create bootable USB drive.
Stage Three-> Prepare your computer
8. Next, go to the desktop control panel > Administrative tools > Computer Management > Storage and then select Disk Management to navigate to the disk management tool on PC.
9. Right click on C Drive and select Shrink Volume in the bottom window pane.
10. Enter the amount to shrink (min 20GB), which will be the size for Windows 10 drive. Click Shrink to allocated space of PC hard drive.
Stage Four-> Install Windows
11. Reboot the PC. Press F12 as soon as the system reboots in order to select your boot device. Select USB drive and press Enter
12. In Windows setup, click Next and follow onscreen to install Windows 10.
13. Select the partition that created which marked as “unallocated space” and click Next.
Note: Windows will take a few minutes to copy files.
14. Once finished copying files, system will reboot and display a boot menu.
Stage Five-> Finalize Windows Install
15. After PC reboot, in boot menu select Windows Technical Preview. It will copy more files and then reboot again.
16. Select Windows Technical Preview a second time, after the system reboot.
17. In express settings, click “Use express settings.
18. Sign in to Microsoft account or create a new account.
19. Verify account by entering the email address and then key in the code that received from Microsoft emails.
20. Select “Set this up as a new PC instead” so that can default install of Windows 10. Click Next to enable OneDrive.
Windows will take a few minutes to finalize your settings. Windows will present with the same boot menu and given the choice of existing Windows or Windows 10 Technical Preview.