How can I determine which of my hard-drives has a crappy connection?

So I recently bought a new case with a 6 front-loading drive trays, all of which I filled with hard drives. All the drives are in a RAID, but it looks like there are problems.

On the console of the connected monitor, I get those low-level SATA errors showing up, which lead me to believe that one of the drives was dying. None of them were failing SMART, so I ran long drive tests on them to see if I could locate the culprit that way. All of them passed :/

Now I'm guessing that perhaps a long SMART test is initiated within the drive itself and isn't performed by the computer. So now I'm thinking, probably what's going on is one of my SATA cables or a removable tray connection is bad.

So my question is, is there a simple way I could check this without going the brute force root of unplugging each drive one-by-one?

Any help would be greatly appreciated.

Thanks!