Normally yes, but some psu have varibale resistors inside. With this you can manually adjust the rails. But don't know how napalm realised that.

On the other side, i can't see any advantage in rising the rails over the demanding 12.00V. Maybe if you use a poor psu, which drops way under maybe 11.90V it could possibly a advantage. But to be honest i don't think anyone here in the thread will not have have a state of the art psu.

Played a lot with adjustable rails in the past, but if some component is holding back the oc i couldn't get them higher with raising the rails. It was just to get the placebo effect of higher and "stable" voltages. But i always used some of the best psu you can get at that time.