Make no mistake: two hard drives are better than one.
If you’ve installed a new hard drive and are wondering what to do with the old one, there are two immediate things that you can use it for: speed up your PC or protect your system from a crash.
Having said that, here are 4 things that you can do with the second internal hard drive:
#1: Experiment with other operating systems
One advantage of having a spare internal drive is that you don’t have to partition it if you want to experiment with other operating systems. For example, you can try a number of Linux distributions or even latest the (but unstable) versions of Windows.
#2: Segregate your data from Windows
Separating your library files from the directory that contains your Windows installation by using this old drive is beneficial as it protects both the installation and library files. If you have an SSD, place Windows on that drive or even if it’s a smaller one.
#3: Turn both drives into one very fast drive
If both the drives are of the same capacity and the motherboard supports it, then it’s a good idea to set up a RAID 0 which will turn both these slower drives into one very fast drive.
#4: Turn the internal drive into an external one
For this, remove the spare drive but not before purchasing a SATA-USB drive enclosure that costs less than $10. This will convert it into an external drive and that can be used for backup. Or else, you can use it to store extra files when your main internal drive runs out of space.