A technician has just installed a new power supply into a desktop computer and now the computer will not turn on. Which of the following is the MOST likely cause?（）

• A、The voltage selector switch on the power supply is set incorrectly.
• B、The 3.3v power line is connected to the wrong input on the motherboard.
• C、The new power supply voltage rating is too high.
• D、The 12v power cord is installed incorrectly.