where do you live? in USA it stays at 115v only switch it if you are in europe. US domestic power is at 120 volts and 60 hertz, most of the rest of the world has 220 volts at 50 hertz.
Yes. That is because your electrical outlet only has 120V available. When you switch the PSU's voltage selector, all you are doing is telling it that it is plugged into a 230V outlet... which it isn't. Therefore the voltage divider is only supplying the system with half the necessary voltage. Never change that switch from what ever voltage it is plugged into.
this guy sounds like Eddie Van Halen, and every other weirdo who then takes a VariAC to crank UP the AC on their gear to get MOAR TONE!!! except the opposite, he's emulating a brown-out or a dimmer... hmm...
hey, if you want your CPU running at MAX, bypass the PSU and just run 120V AC to the whole mobo.
Your cpu only needs 1 volt. You are lucky your are selecting a higher voltage than you have available and not a lower one, or you would hear a pop and smoke would come from the unit. Did you notice the switch is difficult to get at? This is to stop the untaught from moving it.
Messing with it is dangerous.