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How to Choose a PC Power Supply

NOTE - This page still needs to be expanded and neatened up but does currently have a lot of useful information.

To choose a PC power supply, make sure it has the following:

Keep reading for more information about how to do this.

TIP - read reviews ( I like Tom’s Hardware )

Newegg has a really helpful power supply calculator that can help you find out how many watts you need: HERE

Why it matters:

Things you might want to consider:

PSU Brands and Quality

A lower quality PSU can cause problems. You probably want to make sure that you have a good name brand. A name brand does not necessarily mean good quality though. These days I prefer EVGA. You will probably be fine with any of these brands:

Power Supply Ratings and Features

Continuous power - “Maximum Power” of a power supply is the continuous (stable) power delivered consistently. Peak power - max power the PSU can deliver, a surge ( like 15 seconds )

Make sure you have enough continuous power.

Protection Features:

Efficiency Rating:

300 watt PSU efficiency example:

A more efficient power supply will produce less heat resulting in the following:

What is 80 PLUS certification?

This is a certification that indicates that a PSU meets specific efficiency requirements. PSUs are rated by independent labs.

% of Rated Load 10% 20% 50% 100%
80 PLUS 80% 80% 80%
80 PLUS Bronze 82% 85% 82%
80 PLUS Silver 85% 88% 85%
80 PLUS Gold 87% 90% 87%
80 PLUS Platinum 90% 92% 89%
80 PLUS Titanium 90% 92% 94% 90%

PSU Rails

+12V rails

other rails …….

Form Factors

Match your case and system board.

AT - legacy




SFF - (Small Form Factor) - small power supplies

SFF From Factors


Main connector

Processor power connector

4-pin Molex connector

SATA power connector