Hard drive clicking even after switching drives
I was just surfing the web when my hard drive started to click. It sounded really bad so I turned it off. I was able to boot into safe mode without it clicking. It sounded fine and I ran first aid on the drive and nothing was wrong. I was still skeptical that my hard drive was about to fail so I replaced it and tried again to boot it up and it continued to make a clicking noise so I shut it off. I have no idea what what the problem is since when I switched the hard drive it was the same noise.
Update (06/01/2016)
I replaced the optical drive with a hard drive a while ago so I able to still boot the computer just not in the main hard drive slot. Any other hard drive I tried there made the clicking sounds and so I replaced it with a dead SSD so that my computer would boot and there wouldn't be horrendous noises.