My Blue Orb was defective, I think... It vibrated more than it should have. I left it running for three days after installing it, when I came back the GF2 no longer worked.
As for under-volting, you basically connect the +5 & +12 volt wires to it. +5 to the negative side, +12 to the positive side I believe is how it goes. The result is 7V, slightly less airflow, & a much quieter fan.
If you do some searching, there are threads here with much more detailed instructions on how to do it.
Viper GTS