TeraByte Unlimited

My new desktop computer, a Lenovo Legion, comes with Windows 11 pre-installed on its 256GB solid-state drive. A second, independent 2TB SSD was installed for supplementary data storage. My plan is to set up dual boot, which means I can install Windows 10 on the new SSD and then choose between the two operating systems when I boot.

The problem is that I don't have Bootit UEFI installed, thus I get a box warning me about it whenever I attempt to install Windows 10 on the new drive. Could you please provide some guidance on how to set up the dual boot?

Thanks for any help!

well, you'd install BIU, then install Win10, it should add the boot item automatically. The key for any install of an OS is to ensure you boot back to BootIt then boot from your boot media for install (don't boot another os, then from there boot or otherwise attempt to install the other OS, until you have booted back to BootIt). This is so that the renamed directory is put back in its unique place otherwise the other OS would try to use those same files (if you did it that way, you can use the OSI option on a boot item, but most want it separate).