This is all about dual booting on Surface Pro 3.Unlike other systems dual booting with Windows 10 Technical Preview on Surface Pro 3 is not an easy task. To get it going you have to do the followings:
1.Firstly grab the latest drivers of Surface Pro3.
2.Now disable Bitlocker. Shrink the C: drive to 40 GB via Disk Management. There is no need to format the partition.
3.Create a USB Boot ISO for Windows 10 Technical Preview with the help of ‘Rufus’ .Once done reboot.
4.Do some setting changes in BIOS. Set ‘Secure Boot’ to disabled .
5.Boot to Windows. Choose > Settings > Change PC Settings >Update and Recovery > Recover Under Advanced Start-up choose Restart now.
6.Surface will start booting from USB.