What color wire is the 5v connector on the standard four pin connector (i.e. the one that plugs into the hard drive)? Also, the black ones are ground wires, correct?

yellow is your 12v, red is your 5v and yes the 2 black wires are your ground

Thanks so much!!! That is what I needed.

so if we connect both the 12v and the 5v to a single cable that goes to the fan and then a black outn going out of the fan would it go at 17v?? our would i get a shourtcircuit??

got me on that one... but knowing me, i would try it, ive got an extra PSU kickin around that i try that kinda stuff on

I don't think you would get 17v because the connection is parallel . I think it would increase the current (amps). But I'm not sure what the voltage would be. I don't know exactly why, but it is not good to put two different voltages in parallel. Maybe try it with an old PSU and play aroudn with a multimeter.

No.

Formula is v1 - v2 = vT where v = voltage.

So, you'd end up with a 7v line if you connected the 12 and 5 together. 12v - 5v = 7v

To get 17v you'd need a 12v line and a -5v line. 12v - -5v = 17v

that is very nice to know! So if I ever need 7v for a project, I know where to look.