I'm looking to learn more about power requirements and such that a Power Supply/Computer work with.
I see this image
and it has a lot of different pin layouts for various things and such.
For a few projects of mine I'm looking to connect up to the power supply.
I've heard I only need 1 12V+ and 1 ground, but I also need a 5V+ and a ground for another part of the project.
I'm curious if it matters where this is taken from on the whole?
I'm also curious, looking at that 24-pin connector, why the MB needs all of those values? 3.3v, 5v, a bunch of 12 volts….
Does that all get split into individual things or…? I see the VGA connector is 3 12V, and 5 grounds, so I'm curious if individual parts of the GPU require 12V+ or if it requires 36v total, or whatnot?
Essentially I'm just curious how power works, how you know how much voltage, and amps and such you need to power your devices, and all that stuff with connectors and such, to make sure you have the proper power inputs and such?
Any advice is appreciated, thanks a lot!
Best Answer
As Passerby says, the main reason why there are several wires for any given voltage is that a computer may require tens of amps, so one wire by itself isn't enough.
The reason for all the voltages is largely historical. For many years, the standard voltage for digital logic circuits was 5V. Many circuits still run at 5V.
However, later chip designs could be made to work at lower voltages, and would run cooler when powered at a lower voltage. So 3.3V was added to the power supply.
+12V is mainly used for powering motorized things, like disk drives and fans. It's also needed for RS232 serial ports. RS232 also requires -12V, so power supplies often have a low-current -12V line as well.
The 5Vsb line is a "standby" power line, to keep some parts of the computer powered on while the computer is in "sleep" mode.