After installing a second processor and corresponding heatsink into a server， an administrator notices that the new processor is not showing up during POST.  Which of the following could be the cause of this issue？（）

• A、 The power supply is not sufficient to power the server.
• B、 The voltage regulator module （VRM） was not installed.
• C、 The IRQ setting was not set.
• D、 The DMA setting was not set.