And this time — a second and final deep-dive into power supplies.
**Why do we even need a power supply in a computer?**
The power supply's primary job is to convert the alternating current (AC) coming from the wall outlet into direct current (DC). It also steps the voltage down to the levels required by the various components (12V, 5V, 3.3V).
Cheap power supplies sometimes use (particularly garish) color-coding to indicate the voltage level and function of each cable.
**The key specs to pay attention to when choosing a power supply are:**
**Wattage:** Measured in W (watts), this represents the amount of power the supply can deliver at any given moment.
You should calculate the total power consumption of all your computer's components and choose a power supply accordingly.
**Efficiency:** Energy can either do work or be converted into thermal energy. In every electrical device, a certain percentage of the power drawn is lost as heat rather than doing useful work.
The efficiency standard for power supplies is 80 Plus, which indicates the unit's efficiency rating. Efficiency ranges from 80 percent to just above 90 percent. The efficiency tiers are named Bronze, Silver, Gold, Platinum, and Titanium.
**Modularity:** A modular power supply is one in which cables can be connected and disconnected as needed. The advantage is that unused cables don't clutter the case, keeping things tidy; the minor drawback is a slight reduction in efficiency.
**Active PFC:** Designed to stabilize the current output from the supply. Stable current ensures the computer operates reliably without interruptions.
**Noise:** Other parameters relate to how much noise the supply generates. Zero RPM mode means the supply's fan doesn't spin at all, only kicking in under load when the unit heats up.
**Brand and warranty length:** These are the most important factors to check.
It's crucial to choose a reputable manufacturer and the longest warranty period possible.
**Why?**
The power supply is a component that works extremely hard. It is "bombarded" by high, unstable voltage loads from the outlet, and the internal components responsible for handling that voltage need to be of especially high quality in order to survive over the long term.
In cheap power supplies, these components wear out quickly and can even explode, causing a drop in the power the computer receives and ultimately a complete failure.
A quality power supply can also offer a degree of protection against lightning strikes, potentially saving the rest of the computer's sensitive components from damage that would lead to performance degradation and various faults — though it is not a substitute for a dedicated surge protector.
*Pictured: A Corsair modular power supply, rated at 1000 watts, with an 80+ Gold efficiency rating and a 7-year warranty.*