Very quick 12v question...

[Mac42]

Each power connecter (for harddrives and such) has 4 wires: +5v (red), +12v (yellow), and two grounds (black).

When I wire something up to +12v, does it matter which ground I use (thought I saw that one was 5v ground and one was 12v ground)?

Basically will grounding +12v on a -5v ground (if that's the case) affect my +5v line (it seems low, and goes below 4.5v with overclocking, though I'm sure there are larger factors involved in that).

[Carnil]

It doesn't matter. The ground wire is at 0 volts.

[Crazy Jayhawk]

The only reason they're called the 5 and 12 volt grounds is because of which wires they're next to. You can use either one. The power socket on my Zip drive actually has the two ground pins soldered together.