I got an Antec TPQ 1200 OC which allows you to adjust the 12V in a range of 11.8 to 12.6v. I got it mainly for the extra PCIE 8 pin cables, but ain't complaining about knobs to turn.
What advantage is there to bumping the 12v up (or down)?
Most everything of import ultimately runs at far less voltage so I'm at a loss to see any benefit aside from a tiny bump in fan speeds......and since I run fans and pumps on a separate PSU I can't even justify that.