Hello everyone. So, part of the HDDs I bought for practicing DR had either severe media damage or very weak heads. However, thing's that all of them were at least barely usable (you could plug them into your computer and use them at some extent, they could be super laggy or corrupt practically whatever you put in them).

I decided to go ahead and buy a USB -> SATA bridge just for sake of simplicity, so that, after checking them out on a proper on-board SATA interface, I could plug them in it and just copy a bunch of movies, music, etc. (ideally, to be able to visually tell whether the media keeps being readable and consistent as time goes by).

The manufacturer of this enclosure claimed that you would only need the external PSU just in case you wanna use a 3.5" drive. So I went ahead and plugged one of the known kinda-working 2.5" drives (one that I recently tested on a real on-board SATA port) and it started clicking. I said, well, maybe it simply died, so I grabbed another one, same thing. I decided to go back to the previous one and now plug in the external PSU, and boom, it works. However, the other one is still clicking but sometimes detected. I kept trying with that one (presumably thinking it could've just been a casual sudden death) but now without the external PSU, and then I heard a pretty high-pitched sound coming off the platters, so I assume it's a head crash. Plugging any other 2.5" Hitachi disk of the same model shows the same behavior, so, my question is: is it possible to actually cause a head crash by not having the 12v rail up? Could it be that the heads tried to move while not flying off the platters and with the platters not actually moving?

At some point I even decided to try again with another drive, I heard the same noise and quickly unplugged it. This time though, it doesn't seem like it's got any damage (at least not in the short term).

Well, that's it for now, hope you can give me a couple of clues about what could be going on here.

Thank you in advance!