What is the function of the power supply unit in a computer?
Answer: B
Correct answer: It converts mains AC into the low-voltage DC the components need
The power supply unit converts the alternating current from the mains - 230 volts in India - into the low-voltage direct current the components require, chiefly +12 V, +5 V and +3.3 V, delivered through standard connectors. Its capacity is quoted in watts, and it must exceed the total draw of the components, with the graphics card and processor usually accounting for most of it. Efficiency is rated by the 80 Plus scheme, and a more efficient unit wastes less energy as heat. The second option describes an UPS, an uninterruptible power supply, which is a separate external device containing a battery. It provides enough time to save work and shut down cleanly, and also protects against surges and voltage fluctuation. The PSU is a common cause of intermittent faults that look like something else - random restarts and instability under load - because an inadequate or failing unit fails only when demand rises.
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