How can I tell which HDD died?

RedDirt

Honorable
Mar 6, 2016
10
0
10,510
I was playing with a 'new' toy, a HP Pavilion Elite m9290a that was sitting around for a few years. I noticed the hard drive was a bit noisy running, bit like an old 386, I thought that wasn't abnormal. But then it started doing the click of death. Then soon after slowed to a crawl, then blue screen, with Stop Error. It can't reboot. I've got as far as the same stop error. So I'm just assuming hardware failure. This computer has two 500GB hard drives. How am I now able to tell which one is bad?