I have a Transcend StoreJet 25M3 1 TB drive, I connected the signal cable and the power cable to one of my raspberries, and it worked. The device booted and it is stable. So my advice is to try it and see.

Thank you!
I may rethink it then. Thanks for the advice.

It may be a good idea to run rpi-update, but when I try to do that I get the following:
What is wrong?
Where do I find this rpi-upgrade?

mahjongg said: Although... the 5V is only used to feed a 3.3 Volt regulator, as the R-PI (SoC) itself runs on 3.3volt, so it probably will run on much lower voltages than 5V (like 4.6 Volt). But the "5V" also goes to the R-PI's USB connectors, and what is connected there might be less forgiving. Acc...