Hi all, I have been advised to replace my internal HDD of my 2012 iMac. I was wondering whether it is possible and feasible to switch the system drive from the internal HDD to an external HDD? Could I just buy an external HDD and tell the iMac to run from this, instead of going through the hassle and risk of replacing the internal HDD? Also, if I did this, would there be any negative impact on computer performance? Thank you!