The power switch sometimes referred to as a voltage selector switch, is a small switch located on the back of most desktop computer power supplies (PSUs). 220V/2
Correct Power Supply Voltage
There is no single answer as to which voltage setting you should use as it is determined by the country where the power adapter is being used. For more information on what voltage to set the power supply voltage switch to, see the Voltage Valet Foreign Outlet Guide.
For example, if you live in the United States, your computer’s power switch should be set to 120V. However, if you are in France, for example, you should use the 230V setting.
Important Facts About Power Supply Voltage
The power supply can only use what the power supply provides. So if the outlet transmits 220V power, but the power supply is set to 110V, it will think the voltage is lower than it really is, which can cause damage to computer components.
However, the opposite is also true: if the power supply is set to 220V, even though the input power is only 110V, the system may not even boot, expecting more power.
Again, just use the Voltage Valet link above to learn which you should set your power supply voltage to. If the voltage switch is set incorrectly, turn off the computer, and then turn off the power switch on the back of the power supply.
Unplug the power cord completely, wait a minute or two, and then toggle the power switch to the correct position before turning the power back on and reconnecting the power cord.
Since you are reading about changing the supply voltage, it is likely that you are using your computer in a different country. Since you can’t use an AC adapter without a power cord, keep in mind that you’ll likely need a plug adapter that fits the AC adapter’s plug.
In the example, the NEMA 515 IEC 320 C13 power cord shown below plugs into a standard North American spade outlet, but will not plug into a European knockout wall outlet.
Some power supplies do not have a manual line voltage switch. These power supplies automatically detect and set the input voltage, or they can only operate within a certain voltage range (usually specified on a label on the power supply.
You can install a power supply by opening the computer case. However, some parts, including the voltage switch and power button, are accessible from the back of the computer case. Most line voltage switches are red, as in the example on this page.
It may be between the power button and the power cord, but if not, somewhere in that general area. If changing the supply voltage setting with your fingers is too difficult, use something hard like a pen to change the direction.