The PSU (often referred to as the power supply) is used to power up all of the computer components inside the computer case. It’s also used to power up some of the external devices as well. For example, an external USB hard drive that doesn’t have its own power source (it’s not plugged into the wall) will be using power from the power supply. As the power supply is used to give life to so many components, there’s no doubt that it’s an important part of the computer build.
Cheap vs Expensive Power Supplies (PSU)
PSU Do NOT buy a cheap power supply a cheap power supply will often have little to no safeguards such as over current and over voltage protection. Also, they often only have a one year warranty and tend to stop working after about a year and a half. When they do malfunction, they’re more likely to kill your other PC components at the same time. A good power supply on the other hand will often have many safeguards such as:
OVP (Over Voltage Protection)
UVP (Under Voltage Protection)
OCP (Over Current Protection)
OPP (Over Power Protection)
OLP (Over Load Protection)
OTP (Over Temperature Protection)
SCP (Short Circuit Protection)
They will also have good warranties (often 3 to 7 years) and are very unlikely to ruin other PC components if they do develop a problem. So the message here is clear… don’t buy a very cheap power supply.
All power supplies vary in how efficient they are when using power from the wall. Some waste more power than others which will give you a higher electric bill and some waste less which will lower you’re electric bill in comparison. Most power supplies these days have a power efficiency rating. These ratings are shown next in order, starting with the most efficient. Power Efficiency Ratings
80 Plus Titanium
80 Plus Platinum
80 Plus Gold
80 Plus Silver
80 Plus Bronze
The ‘80 plus’ rating at the bottom of the list is the least efficient, but this is still better than a power supply with no rating at all. The upsides to getting an efficient power supply are:
You’ll save some money on your electric bill
They generate less heat which means less fan noise
They’re likely to last for longer So are there any downsides to getting one of these power supplies? Well, the more efficient a power supply is, the more it will cost you to buy in the first place. So it’s good to get a balance that’s right for you.
Power Supply’s Physical Size (PSU)
An ATX power supply will have a standard size of 15cm width and 8.6cm height (or at least very close to that measurement). But their depth will vary, often between around 14cm – 16cm. An ATX power supply should be used with an ATX or E-ATX computer case. mATX power supplies also have a standard size of 15cm width and 8.6cm height (or at least very close to that measurement). But the depth can vary, often between about 10cm – 13.9cm. A mATX power supply should be used with a mATX computer case. Some mATX cases can also accept an ATX power supply, but not all can, so stick with a mATX power supply for a mATX case if you’re uncertain. A mITX computer case will use a small form factor power supply such as a mITX, SFX, TFX or a mATX. All mITX cases and small form factor power supplies vary in size, so check before you buy, if this is what you’re going with.
Power Connectors (PSU)
Attached to the power supply itself will be many cables. At the end of these cables will be various power connectors. These connectors are used to give power to the components inside the computer case such as the motherboard, hard drive, DVD drive and so on. Next are the power connectors you’ll come across on most power supplies, along with a description for each one.
This connector is used to give power to the motherboard. Most motherboards these days need a 24 pin power connector as shown in the picture (2 rows of 12 pins). Some use a 20 pin connector instead. By the way, many power supplies will be advertised as having a 20+4 pin connector. This means that it has 4 detachable pins so that it can be used as a 20 pin or a 24 pin power connector to power the motherboard.
These connectors are used to give power to hard drives (including hard disk drives, solid state drives and hybrid drives) and optical drives (including DVD drives and Blu-ray drives). The amount of SATA power connectors a power supply will have, will vary.
These connectors were used a lot more years ago, but are not used very often today. They were used for hard drives, optical drives, some dedicated sound cards, case fans and various other components. It’s unlikely that you’ll need one of these for a new computer build today, but they are still used now and then and are included with almost all power supplies.
This connector is used to power up a floppy disk drive. I don’t know of anyone that still has a floppy disk drive any more. They were very popular years ago but they’re never installed in computers today. But this power connector is sometimes still used for other PC components such as various card readers and a few dedicated sound cards. As this power connector is so rarely used in modern computers today, it’s sometimes not included at all with some power supplies.
These power connectors are used to give power to the graphics card. The graphics card that you buy may need no PCI-E power connectors, or it may need one or two 6 or 8 pin PCI-E power connectors. The graphics card that you want should clearly state what it needs. One ‘6+2 pin PCI-E power connector’ can be used as a 6 pin or an 8 pin PCI-E power connector.
These power connectors are used to give power to the CPU (you plug them into the motherboard). Most motherboards these days will use either an 8 pin CPU power connector (described as an ‘EPS 8 pin 12 volt’ power connector), or they may use a 4 pin CPU power connector (described as an ‘ATX 4 pin 12 volt’ power connector). Most power supplies have both, as the EPS 8 pin 12 volt power connector can often also be split into two, to give you two ‘4 pin ATX 12 volt’ power connectors.
Modular vs Non-Modular
When using a modular power supply, it’s possible to detach all of the cables from the power supply itself. A semi-modular power supply is one that has some detachable cables and a non-modular power supply has all of its cables permanently attached to it. The advantage of a modular power supply is that you only need to install the cables that you need for your PC. This will allow for better air flow inside the computer case, keeping everything a little cooler. The advantage of a non-modular power supply is that you don’t have to figure out where each cable should be plugged in (into the power supply), though this is normally fairly obvious. Also, you’ll never lose any of the spare cables. It doesn’t matter whether you choose a modular or non-modular power supply. It really just comes down to which you prefer.
Silent And Near Silent Power Supplies
Many power supplies have a fan inside them. The only noise you’ll ever hear from a power supply (excluding coil whine that some suffer from) is its fan spinning round. In an effort to try and reduce noise from the power supply, many manufacturers are now designing them so that the fan will only spin when needed. If you’re interested in a power supply like this, look out for ones that are advertised as having a ‘Zero RPM Fan Mode’ or ‘Fanless Mode’ or something along those lines. Some models don’t even have a fan which make them completely silent all of the time. Those fanless power supplies are often used for media centre computers though and are not used so much for gaming computers.
How Many Amps (amperage)
Once you’ve used the eXtreme Outer Vision website for its power supply calculator (as mentioned in the previous section), the results on the website will show you how manyamps your computer will potentially use on the +3.3 volt, +5 volt and +12 volt rails.
|8.1 A||12.4 A||25.3 A|
When you’re browsing for a power supply (PSU), each one should state how many amps it can produce on the +12 volt rail. Some will also show how many amps it can produce on the +5 volt, +3.3 volt and -12 volt rails as well. But it’s the +12 volt rail that we’re interested in here. If the power supply calculator that you’ve used recommends a power supply that can produce, let’s say, 24 amps on the +12 volt rail, then look for a power supply that can produce 24 amps or more on the +12 volt rail. Here are some websites that you may find helpful when trying to discover how many amps each power supply can produce on the +12 volt rail.
To keep this simple, go for a power supply with a single +12 volt rail. What do I mean bythis? Power supplies with two or more +12 volt rails will have a description such as this:
+12V no.1 = 18 amps, +12V no.2 = 20 amps.
Unless you know what you’re doing, go for a power supply that has just one +12 volt rail. Some power supplies that have a single +12 volt rail are recommended next. By the way, if you are going to use a modified graphics card (for example, you buy an overclocked graphics card, such as the Asus GTX 980 Ti OC edition) then you may need more watts/amps than is recommended by the power supply calculator.
Help Choosing a Power Supply Unit
The latest Cooler Master V450, V550, V650 and V750 power supplies are excellent (they are all within the semi-modular series). They all have a 5 year warranty, great build quality and are highly likely to have all the power cables you’ll need. The V750 has four PCI Express cables allowing up to two graphics cards and the others mentioned here have two PCI-Express cables allowing one graphics card. By the way, they are all single +12 volt rail power supplies. Some of the other reputable power supply brands are Antec, Corsair and Seasonic.
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