Dual boot with 2 hard drives


New Member
I already have Win 7 installed but want to install Win 10 on a separate SSD. I am getting conflicting info saying I should unplug the Win 7 disk first because the Win 10 installation will corrupt Win 7 and others saying I don't have to unplug it first. Which is the correct way? Should I install EasyBCD before or after the Win 10 installation?


Knows where his towel is.
Staff member
W10 is designed to install itself with a pre-existing Windows. (any Windows will automatically dual-boot itself with an earlier existing version)
When the installation has completed you will see that W10 is "boot" but W7 is still "system" because W10 will reuse the existing W7 BCD (but update the boot files to W10 level).

Disk Management flags have the following meanings

"boot" = "this is the system you're running"
"system" = "this is where I found the boot files for the currently running system"
"active" (on the first HDD in the BIOS boot sequence) = "this is where I started the search for the boot files"
"active" (on subsequent HDDs in the BIOS boot sequence) ="this is where I will look if I don't find something in the MBR on the first HDD"

You won't actually need EasyBCD. W10 will do everything for you.
You might like to use it to tidy up cosmetically. The automatic process will probably give you boot choices like "Earlier version of Windows" which you can edit.
It doesn't matter when you install EasyBCD. It's never active during boot. It just runs when you start it on a working OS and it modifies the BCD in whatever way you instruct it, to alter the boot menu next time (and all subsequent times) that you bootstrap the PC.

EasyBCD Basics
I was able to install 10 without using EasyBCD. I disabled the Windows 7 drive first. It boots Windows 10 by default but if I want 7 I hit F12 to select the drive