What happens if you connect to a 3.5 adapter when there is only 2.5 support?

Question

Hard disks

Finishing work with the hard drive that was connected to the laptop, I decided to look for an old drive, 3.5. Just nothing to do. As a result, I found it, after which I attached it to the adapter. He approached. I did not take risks and connect to a laptop, since it was written that 3.5 is not supported. And such a question, what will happen if you connect? How reliable is it? What could be the consequences?

Answer 1

I took the first available disks (old ones), looked at their power requirements. 2.5" does not even ask for +12V. If there is no +12V power on the adapter (probably, this is the essence of non-support), then 3.5" will not start (the spindle motor will not receive power, the disk will not spin up).

Answer 2

3.5 and 2.5 differ only in size and sometimes power consumption.
So it won't fit or won't turn on. It's OK