Secondary drive marked as System/Active

[Persheis]

Hello all!
Just today, I installed my new 1TB HDD in my Windows 7 computer. The main HDD was a 10 years old Hitachi drive, so I decied to replace it, and take the chance to upgrade all the system to Windows 8.1.

I disconnected the old drive, and installed this one in place, keeping a 500GB secondary drive I used mainly for storage. However, as soon as the installation was completed, I was greeted with the Dual Boot screen, asking me if I wanted to boot to 8.1 or 7... This secondary drive has no boot info, nor any SO installed inside.

By checking in Disk management, this secondary drive's first partition is marked as system / active.

How can I "deactivate" and "desystem" this drive so I avoid the dual boot screen?

Thanks in advance!

 

[DataMedic]

Easiest way is to just zero fill the drive using a free utility like Active KillDisk. You really only have to zero fill the first 1% to be sure to wipe out the MBR and partition tables (though it isn't a bad idea to let it run the whole course to test the drive). After that you can just initialize and format it in Windows disk management.

Just be sure you're on the actual disk, and not the logical volume (you want to kill the one that says something to the effect of "fixed disk" not the one with a drive letter "E:").

 

[fzabkar]

IMO the easiest way to reset the active flag is with a partition table editor. Change the boot flag of the active MBR partition from 80h to 00h. This does not damage your data. I use a disc editor such as DMDE, but there are numerous tools that could do the same job.