This doesn't exactly have to do with rockbox other than that my ipod is on rockbox, but there's a thread similar to this about iriver hard drives above, and I imagine this is something of interest to people here so I'm guessing it's kosher. Plus you guys seem more informed than in most places...
I got my hands on a Samsung HS161JQ 160GB drive which came from a 160GB ipod classic, and I tried to hook it up to my 5.5 ipod video 80GB. The connector fits, but it absolutely does not spin up at all. The original and new drives are 3.3V, but the original 80GB drive is 0.5A while the 160GB one is 0.4A. Would that amperage difference preevent it from starting up, or did I just get a dead drive?