Week 1: The Power Supply Unit

This week were going to be taking a look at the PSU, or by it's proper name the Power Supply Unit.

As the name suggests it supplies power. This is probably the most essential component needed for your computer, because without it all your nice fancy components inside your PC wont work.

The PSU is a metal box with a huge fan built in that sits either at the top, towards the back of your case or at the bottom on the base of the case. It generally has lots of different cables coming out of one side with lots of different connectors on – we'll get to these later – that supply power to different components on your motherboard either through direct connections or through cables connected from the motherboard to other components, such as a graphics cards or CD-drives etc.

What the PSU does is convert mains AC power to low-voltage regulated DC power, this is because most of the components require different voltages to work. Also, note that most power supplies conform to modern ATX case sizes, so getting the wrong size for your case should be near impossible.

There are a couple of variations of PSU that you can buy, one is the standard one that should come with all connections needed to power all components in the case, don't worry if you don't have a particular connection because there is most likely an adapter you can buy, such as a 6 pin connector that's used for supplying different voltages to a graphics card, and they will come with another connector at the other end for connecting to an existing connector on the power supply, such as a Molex connector. The downside to these power supplies is that they can dangle everywhere, get in the way, disrupt airflow and generally make the inside of your case look like a section of the Starship Enterprise has blown a conduit. Cable management is difficult at best with this type of PSU.

The other type of PSU is known as Modular or Fully Modular, these PSU's are great because they come with detachable cables, the biggest upside is that you only plug in the cables you need to use, this also helps your case with it's cable management which in turn helps with air flow, which with modern components air flow is key because of the heat they generate.

Your unused or old desktop will have one of these so depending on your use of the computer you intend you might only need the one you have or you might need to replace the one you have because you need more wattage for the components you intend to upgrade to.

This presents a slight issue however that you have to over come. How many watts do I need? Assuming you know the specifications of your existing desktop then you can use this site http://powersupplycalculator.net/ to work out how many watts you need. All you need to do is input your specifications and calculate how many watts is needed, if you intend on upgrading, for example your graphics card to a more powerful one, then just put the model of the GPU you want to use and recalculate the watts needed. Then you get to decide if you want to keep the PSU you have - if it's suitable - or get a new one.

I said earlier we would look at the different types of connectors that are on a PSU. All those connectors will look like you need a qualification in electronics but I assure you, you don't. Each connector has a specific use and once you know what there use is, it's pretty hard to get it wrong, so I'll list them and explain what they are used for:

The 20+4-pin connector:

This is the biggest and main connector that plugs into the motherboard to supply power to the motherboard and other connected components, such as memory and the CPU. Some come with a connector that separates turning it from a 24-pin to a 20-pin connector depending on the motherboards power requirements. It is useful to note that most modern motherboards use the 24-pin connector more commonly, they used to be 20-pin - as standard - but with the increase in power requirements for certain components, 24-pins were needed to supply the correct power.

The connectors interface is usually located on the motherboard on the right hand side close to the memory banks.

The P4 ATX(a.k.a ATX 12V):

This 4-pin connector was added when Intel developed there Pentium 4 processors, this was because the processor needed it's own dedicated 12V power supply. With the latest standards of CPU's the use of an 8-pin connector is needed in some cases. The connectors interface can be located close to the CPU usually on the left hand side towards the top.

The 4-pin Molex:

This connector is the oldest on most standard PSU's. It was mainly used to power older IDE/PATA Hard Drives and other older devices like, CD Drives. Now though with the introduction to SATA connectors and hard disks use of SATA they are pretty much just used for supplying power to fans.

SATA power connectors:

With the development of SATA came new interface types that look nothing like and replaced IDE/PATA interfaces on the motherboard, this also meant new connectors were needed to supply power to the newer improved and better performing devices such as HDDs or SSDs. The connector looks like the letter L in shape, this makes it easily identifiable.

Adapters:

Adapters are used to connect a different connector using one that already exists, such as a 4-pin Molex into a 6-pin ATX connector for your Graphics Card. You can also get Molex to 3-pin fan connectors for if you buy fans that come with 3-pin connectors.

How to install your PSU

Installing your PSU isn't all that hard, first off if you discover the one you already have installed is good enough for what you intend then you have finished reading this article.

But if for instance your upgrading so you can play games, or dabble in some audio or visual editing, you may need to get a more powerful PSU because these types of rigs need quite a bit of power.

So to start off with you want to switch the power off and take out the power cable. Then you want to check to see if you can remove the top panel of your computers case. If you can, great, that will make this process easier, because you'll be able to take the PSU out through the top. If you can't then your going to need to take off your processors heat-sink and fan and maybe take your RAM modules out because these can get in the way and you don't want to damage them.

I have a separate article on how to re-apply the thermal paste and heat-sink HERE.

If you do then take precautions and use an ESD strap – this helps prevent any unwanted electro static discharge from damaging you components – once that's all out of the way and you've put your heat-sink and Memory in a safe place you can then go right ahead and unplug all the cable connectors from the motherboard and internal devices. Then at the back of the case(externally) you can unscrew the mounting screws, once that's done you can slide the PSU out and install the new PSU in the reverse order of what you did to take the old PSU out.

Next week we will take a look at Motherboards, how to install what you can connect to them and specific features to look at when upgrading your old dusty machine for a new purpose.

Milan Tomic

Hi. I’m Designer of Blog Magic. I’m CEO/Founder of ThemeXpose. I’m Creative Art Director, Web Designer, UI/UX Designer, Interaction Designer, Industrial Designer, Web Developer, Business Enthusiast, StartUp Enthusiast, Speaker, Writer and Photographer. Inspired to make things looks better.