3- The power connector for hd on the a590 has only three pins, 12v, 5v and one ground. Though modern harddrives need two ground lines. Should I make a connector which couples the ground line ? (feeding the same ground into both lines, is it dangerous ?) or would my hd be ok with a single ground line ? (currently I'm using it with the case open and standard pc psu with a standard connector.)
Well, ground is ground. The two pins are most likely connected together on the Harddrive, so the A590 connector should work just fine.
If it doesn't, there is no danger in coupling the ground line to both ground pins. (they originate from the exact same place inside your PC PSU).
-Paul
