# Power Supply Types

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Time
12 hours 9 minutes
Difficulty
Beginner
CEU/CPE
12
Video Transcription
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>> This is Lesson 8.1: Power Supply Types & Features,
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The Summary of Power Supplies and Options.
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In this lesson, we're going to talk about
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computer power supplies and how they fit
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into the range of computers and
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systems that we've been talking about here,
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the 220-1001 CompTIA A plus.
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This is our lesson objectives;
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a power overview,
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just an overview of power
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and background information there.
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Then we're going to move and talk about
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the 115 volt versus the 220 volt input,
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24-pin motherboard adapter, and outputs.
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There are three volt, five volt,
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and 12 volt, and the number of devices,
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and the type of devices that can be
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powered from your power supply,
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and we're going to finish talking about
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power supply wattage ratings.
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Let's go ahead and jump right in.
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Let's talk about a power overview.
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Now the power supply in your computer is
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the most important component in your computer.
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Before we jump into that,
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let's talk about power
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and give you a little background information,
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and then we'll talk about
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the placement of the power supply,
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how it comes into the grand scheme of
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things as far as when it's dealing with the power.
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Now the power that is supplied to
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alternating current in the voltage
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of either 120 or 220 volts.
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Your computer operates on DC, direct current power.
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The power supply in your computer converts this,
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it acts like a converter of
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sorts and it converts this voltage to
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a usable power of DC and it
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powers your computer and
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its components with this DC power.
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Now electricity is the flow of
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negatively charged particles called
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electrons through matter,
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and you may remember that from
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old high-school learning and so forth.
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Electricity works the same
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as water flowing through pipes.
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It's under pressure and from
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your supplier delivered to you.
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This pressure is called voltage and is measured in volts.
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The amount of electrons or electricity moving past
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a certain point is known as the current or the amperage.
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This is measured in amps or you'll see A.
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Also, continuing on,
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resistance to electrons is present
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in all type of wires or metal for that fact.
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This resistance is measured in what's called Ohms,
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and you've probably heard of Ohms before.
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Now the amps or volts needed for
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a device to function properly is the wattage it needs.
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Again, somewhat you may be familiar
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with this calculation.
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V times A equals W
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which is volts times amps equals watts,
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and that's how that's derived.
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[NOISE] Key points to remember, pressure is volts.
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Volume flowing is amperes.
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Work is wattage.
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The work that, that source does,
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so that power does,
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that's the wattage,
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and the resistance found in all cables is Ohms.
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You're going to need those key things as
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you start working with power supplies.
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When you're looking on the backs of
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the power supply boxes and you're going to see Ohms,
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you're going to see wattages.
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That'll give you a little background information as far
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as what you're looking at and how to
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determine what you need and how to make
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a better judgment as far as which
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components you're going to be needing for
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a system whether you may be building,
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repairing, or so forth.
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Now electricity is in one of two forms, DC or AC.
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DC which we spoke about earlier is direct current.
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It's when the flow of electrons move in
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a continuous flow in one direction.
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Most electronic devices are powered with DC current.
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Mobile phones and mobile devices,
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all of those are powered with DC current.
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AC or alternating current is when
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the flow alternates back and forth in a circuit.
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Now this is what's supplied to you, the AC current.
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Because it flows back and forth,
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it can travel longer distances,
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hence why the power company supplies you power
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from a long distance away through
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power lines to your home or business.
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Again, AC power comes from the power company,
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and DC is for mobile devices.
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When we spoke about earlier,
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that power supply in your computer takes that AC,
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converts it to DC for it's usable components and parts.
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Again, now the power supply's main job is converting
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that incoming AC and output it to DC,
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so for it's system and its components to
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use the devices on that system.
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It converts 110 volts AC or 220 volts to
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240 volts AC to negative 3.3 volts DC,
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5.5 volts DC, and 12 volt DC.
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Power supplies are available with
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a dual-voltage switch option.
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Some power supplies are auto switching.
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In the back of your computer,
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there's a power supply which we've all seen before,
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that's where the main power cord plugs into right
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there by the fan and there's a little red switch.
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That little red switch if you've
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ever wondered what that was,
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that is your dual-voltage switch options.
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A lot in here in the US,
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we would use for 115.
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If you were somewhere in a part of the country
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or another country that supply 220,
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you would switch that for the 220.
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You want to make sure that your system is powered
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off and sometimes unplugged before you make that switch.
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You don't want to switch it
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while the current is running live,
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that could damage your system.
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That's what the dual-voltage switch is,
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right there in the back of the computer.
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From the power supply,
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you're pricing an octopus of wires of sorts.
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The main wire coming out of that power supply is
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The main motherboard power connector
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is a 24-pin connector.
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It's commonly providing plus 3 volts, minus 5 volts,
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and plus n minus 12 volts
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for the motherboard and the motherboard components.
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Again, it provides plus 3 volts,
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plus 5 volts,
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and negative 5 volts,
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and plus n minus 12 volts.
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Now older motherboards had
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a connector with 20 pins instead of 24.
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The additional four pins were added for a total of
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24 for the PCI Express bus,
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it needed more power,
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so four pins were added.
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The 24-pin connect will work with
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20-pin connectors with four pins leftover.
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Some models allow you to even
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remove those extra four pins
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since you're not needing them.
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Look closely at the 24-pin motherboard adapter
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and this is I would
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say a guarantee safety feature
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so anyone won't cause any damage.
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If you look at the connector itself,
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you'll see some of them are shaped square,
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some of them are rounded,
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some of the ports rather.
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If you look on the connector
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and the motherboard to your right,
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some are square and some are rounded.
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What this means is that connector can only fit one way,
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and because of that,
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there's no way of mixing it up
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and putting in upside down or a different way.
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It orients one way and therefore it connects one way,
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so those you will not
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short your motherboard out or cause any damages.
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Now let's talk about the output: three volts,
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five volts, and 12 votes.
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Different voltages power
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different size devices on the motherboard.
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Power supplies will provide
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both positive and negative voltage.
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Most modern motherboards though do
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not use the negative voltage anymore,
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it was more on the older ones.
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Before we go any further,
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let's look at this image here,
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and this is a gigabyte power supply.
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This is what you see on the back of
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a power supply, all this information.
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You'll see here that it shows that 3.3 volts
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plus 5 volts and it also showed you the amperage.
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Plus 3.3 volts at 30 amps,
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plus 5 volts at 28 amps,
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plus 21 votes at 18 amps,
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12 volts at 18 amps,
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12 volts again at 18 amps, and so forth.
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These are the different voltages that
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your power supplier provides.
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The total wattage would be in
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the max combined total wattage.
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What that means is this is
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the total wattage of the overall power supply;
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550 watts, and it's split
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up over those different rails there: the three votes,
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the five volts, the plus 12, and so forth.
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That's what you'll see on the back of
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your power supply and on the power supply box,
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so now you would have an educated understanding
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of what you're looking for and what this really means.
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This helps you decide and make
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decisions if you're building a system from scratch,
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how much power do you really need
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depending on the components of what
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you're trying to power.
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Now plus 12 volts.
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This normally powers the PCI adapters,
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the cooling fans, the hard drive motors,
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and other modern components.
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These are the heavy lifting,
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it does all the heavy lifting components.
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The heavy devices like
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the cooling fans and the hard drive motors,
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that's what the plus 12 volts power.
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Now the plus 5 volts.
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Plus 5 volts on the modern motherboard is less frequent,
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it's more of the plus 3.3 volts.
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Older motherboards use the plus 5 volts more but
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now our devices are getting more efficient,
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so they're running on plus 3.3 volts.
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Memory modules in two slots and
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motherboards circuits run from the plus 3.3.
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Negative 12 volt and negative 5 volt are not
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widely used anymore on the newer motherboards.
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The negative 12 volt power the older serial ports or
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the integrated LAN ports and some of the older PCI slots.
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Again, the negative power is not
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used that much nowadays.
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Power supply ratings.
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All the devices or components of a system
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requires a certain wattage to function.
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The total wattage of all devices combined is
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the minimum power supply
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you should provide for the system.
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What that means is, if you add up
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all the devices like I said earlier
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and you know you need a certain wattage,
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that's the type of
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power supply you are going to be looking for.
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Also keep this in mind as well,
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depending on the type of motherboard that you're going to
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be using for your system, again,
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if you're building a system or replacing a system,
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it'll tell you are there
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different power supply ratings or
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the versions that you can use for that motherboard.
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Again, let's look at this particular power supply
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on the image on the left.
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This is 1,000 amp power supply,
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or 1,000 wAmp rather power supply, and again,
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it has the different rails: the 12 volts,
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the three volts, and the five volts, and so forth.
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This one is split up over two different rails,
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the 500 watt that supplies it on
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one side and the 500 watt supplies it on the other side,
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and on the right is just a blow up
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of that tag right there on the left.
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Looking here, you can see as
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far as the different outputs
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versus the maximum combined wattage there.
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Another rating that you'll see is the 80 plus rating.
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The 80 plus rating,
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power supplies are graded for their efficiency under
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a voluntary standards called the 80 plus.
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Under 80 plus power supplies are rated from 80 percent to
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94 percent efficiency for a given load,
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and given a badge with
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metal labels such as bronze; 85 percent,
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gold, 90 percent,
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titanium, 94 percent levels.
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The better the efficiency,
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the less power the supply waste.
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If you had, like our previous slide,
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a 1,000 watt power supply and you
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had an 80 plus titanium rating,
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that means you're getting that full
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1,000 watts with hardly any loss.
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It's a 94 percent
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efficient as far as the power it's supplying,
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it's not wasting any power.
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That's what these powers of rating are for.
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Now when a power supply is selected,
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it should cover the system requirements to power
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all the devices with a little room to grow.
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You may even want to use a 50 percent rule.
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If your devices add up to say for instance, 420,
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450 watts, you may want to increase that by
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50 percent for room to grow if you know you're
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going to be adding more devices to that system.
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As a general recommendation for a new system,
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use at least a 500 watt power supply.
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One thing to note that on some
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of the information that we went over,
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the CompTIA A plus 1001 Exam does not require
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calculations to figure precise
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wattage needs for a particular system.
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Just know this information that we went over.
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Power supplies.
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We talked about power in general,
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an overview of power.
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We talked about the 115 votes plus the 220 volt inputs.
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The motherboard adapter, the 24-pin versus the 20-pin,
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and the outputs that's used nowadays,
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the three volts,
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five volts, and 12 votes,
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and the number of devices and
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the type of devices to be powered,
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and we finished off with power supply ratings.
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That is our lesson for today.
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We will see you in the next lesson.
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