As long as the Hard Disk works,you can use it,no problem. But remember,if you store all your valuable data in that,it's prone to failing,and you may lose all your data,which means you may need to have the backup of important files on another HDD.So,it's not advisable to reuse an old HDD in a new build.Though,if you don't care about losing some data,of course you can use it.It won't harm your PC in any way,and may well prove to be a great addition to storage space.