New SSD but I want to connect my old HDD

[MeisterENOX]

So I just installed a new SSD in my system and did a fresh install of windows on it, I wanted to be safe before doing so and I simply disconnected my previous HDD with the files and OS still on it. Would it be safe for me to connect the HDD to my system anymore or will there be an error becasue there is an OS on it? I just wanted to know becasue I really wanted to transfer some files to the SSD as I can see that all is running fine.

 

[SkyNetRising]

Would it be safe for me to connect the HDD to my system anymore or will there be an error becasue there is an OS on it?

Yes, it's safe.
You just have to make sure, that boot sequence in BIOS is correct after connecting HDD.
There will be no error. Your system will either boot from SSD or HDD depending of boot sequence settings.

 

[USAFRet]

So I just installed a new SSD in my system and did a fresh install of windows on it, I wanted to be safe before doing so and I simply disconnected my previous HDD with the files and OS still on it. Would it be safe for me to connect the HDD to my system anymore or will there be an error becasue there is an OS on it? I just wanted to know becasue I really wanted to transfer some files to the SSD as I can see that all is running fine.

Verify the boot order, ensure that it cannot boot up from the old HDD, and you're fine.