Step 2: Confirm The Voltage Setting - HP Compaq 4000 Pro SFF Quick Setup Manual

Step 2: Confirm the Voltage Setting

Ensure that the voltage select switch for the power supply is set to the
correct voltage for your region (115 volts or 230 volts).
CAUTION:
however, you should verify that the voltage selection is compatible
with your local power specifications. Failure to do so could result in
damage to the computer.
2 Chapter 1 Quick Setup
You should not need to change the voltage setting;
ENWW