Let me chime in here. Inside your powere supply there is basicly the
following supplys.
+12V
+5V
+2.5V
-5
-12
ground
The connecter that powers your computer, including the drive
connecters are soldered to the same place in the supply depending on
the voltage. For example if there are 5 +5 wires coming out of the
supply there are 5 holes drilled into the Pc board and soldered onto
the same trace on the board. So an answer to your question feal free
to use either black wire on your connecter.
