I'm left to guess this is some upgrade to an old machine. Some old supplies have issues such as not being rated for new hardware plus age. At just a few years old, a PSU can be half the capacity as new.
There's another issue in the motherboard choice. One of the PCie slots is x16, the other is x4. Some video cards will not come up in the x4 slot.
The Volts is an odd question. The ATX connection is standardized and you should not be changing the voltages.
I've just got a new gigabyte a75m-d2h motherboard and when I turned it on, nothing happened. I'm guessing it's my PSU.
My PSU is LC-B350ATX 115/230V.
What PSU should I get?
How do you know how much volts a motherboard requires?