Power Supplies

Choosing a power supply for your computer is a vital stage in the successful construction of a computer, being cheap on a power supply can impact both performance and system reliability at it's core a power supply is a split voltage device operating at 12V+, 3.3V+ and 5V+ which is basically a what we call a "voltage divider" (not the entire story we are ignoring the full bridge rectifier stage that converts AC-> DC but you get the picture) each of these rails as they call them are designed with a specific operational regulation tolerance the better the tolerance usually the better the power supply, other factors include the kinds of capacitors and other components used, all systems I personally build will be gold certified power supplies. However I should clarify about the difference between a single rail and a multi rail unit. Under many power supplies the rails are often "merged" into a single rail where the entire max power delivery in watts is shared among all those rails together. A multi-rail power supply isolates more restrictively how much power can be delivered to the rail total.

Power supply separation

All computer power supplies are separated by two sides the primary (AC) facing side and the secondary DC side. The power coming from the AC is converted into DC on the secondary side splitting out the different rail voltages. Problem with cheap components on either the primary or secondary side is cheap capacitors, inductors, rectifiers result in poor load regulation on the primary side and also impacts the filtering that is added to the DC side. On a DC circuit typically your waveform is square wave, of consistent power, the concept of "ripple" is how much noise is in that outputted signal, ripple leads to peaks high which may go beyond the regulation threshold, or load tolerance, which is how far that consistent square wave deviates from the normal 12V+ or 5V+ or 3.3V+ or any other rail.

• AC Primary - Capacitors, Rectifiers, Inductors, and other components to smooth out and filter before passing to the secondary side.

• DC Secondary - Further filtering, voltage splitting, and digital intelligent load management, via electronic components.

Mixing Power Supply cables

The most blunt thing I can say is DO NOT DO IT. Every power supply manufacturer for the cables terminating in the power supply are often a very specific method of termination their power output pins and configurations are often specific to every manufacturer and if you mix cables from say ASUS with a CORSAIR PSU your motherboard, power supply or any other component is likely to die a fiery death. This also goes for non-extension PSU cables, always obtain the sleeved cables if they must terminate at the power supply from the manufacturer if you don't as state above you and your PC will have a very bad day. Extension kits on the other hand if they terminate at the 24pin cable end which plugs into the motherboard or the CPU 12V / EPS 12V connector, or the PCIe power connector is fine because these extensions are connecting to the IEEE standardised cable sockets and so have no issue with cross compatibility.

Power supply Safety Features - Power supplies employ a number of safety features which you should look out for which are critically important to the function of your system overall. They take the form of OCP, OVP, SCP, OTP and OPP

• Over Current Protection (OCP) - Is a safety feature that should be all power supplies you decide to purchase it prevents too much current from being drawn down the single rail or multirail of a power suplly.

• Over Voltage Protection(OVP) - Is similar to OCP but this prevents overvoltage, that includes the inrush from the wall socket and the voltage being passed down any of the power cables.

• Short circuit protection(SCP) - Electricity will always want the shortest path to it's destination the lowest voltage potential path which the quickest to get to, short circuit protection prevents a power supply from being shorted to earth and being a danger and typically all the power rails responsible for the option of the power supply are protected with SCP

• Over Temperature Protection(OTP) - In the event the internal temperature of the power supply exceeds it's thermal limits OTP will trip an example would be if the power supply was reaching 95*C on some of the capacitors this will likely trigger an OTP event.

• Over Power Protection(OPP) - The total amount of power on each power rail can only be a certain amount as a result if the amount of power being drawn which is the voltage and amperage combined P = IV (power) = Current * Voltage OPP will likely trip if it exceeds that rails maximum provided power for example if the 3.3V and 5.0V rails are merged into 150W watts and they exceed that OPP will trip.

The combination of all these features makes power supplies safer and more reliable preventing fires, an damage to your computer systems.

A note about poor quality PSUs

Power supply units which are poor quality do not usually have the appropriate safety protections for your system or the right regulation of noise free power for high end components several considerations should be made when choosing a PSU. main safety features are relate to several core ideas, OCP (Over Current Protection), OVP (Overvoltage Protection), OTP (Over Current Protection), and SCP(Short Circuit Protection). Starting with OCP Overcurrent protection can kick in if there is far too much current being pulled down a single rail or multi rail configuration current is the amount of electricity in the form of electrons passing a single point in 1 second it's why it's commonly referred to Coulombs per second or 1C/S where 1 Coulomb is several million electrons, OCP kicks in and will shutdown the entire computer and power supply, this works in conjunction with OVP or over voltage protection, as well as OTP this is the detection of high temperatures within the PSU and it will trip the thermal safety switch and again shutdown the entire system, without these features you are at risk of possibly hurting yourself, your computer or both. SCP is in the event you cause a total short to ground event again the PSU should kick in Short Circuit Protection when a short circuit event occurs often saving your system from being destroyed due to it. Cheap power supplies may not have these safety functions or they may have poor monitoring and regulation of them, and I can tell you this now computer power supplies on the very high end can deliver upwards of 150A close circuit short it is potentially lethal, another situation is a cheap power supply may have AC current leakage where the main shorts straight down the rails to you, or your computer, which is straight 240V or higher if a capacitor fails which is also potentially lethal. If it fails to trip at 150A closed, this can also lead to another problem, when you have a cheap PSU rated for 850W it probably will never be able to supply that much power, and likely catch fire and explode at those output levels.

Power Regulation

Power supplies when they are tested have various parameters which are desirable, one of those is load regulation, when a power supply is put underload the rails tend to drop a bit, if the power regulation of the rails is good enough this will only deviate a few percentage points, but on terrible quality power supplies this management may fall well outside the desirable limits, power supplies which have quality power delivery will be able to both sustain the power they need to components and tightly regulate the ripple which is how much the voltage changes under load better quality components have better regulation on these components and generally the cleaner the signal given to components the longer they last and the less glitches and problems you have with components.

Independent Power Supply certifications - There is a few independent certification bodies responsible for verifying and qualifying power supplies, one of these independent operators is a organization called Cybernetics they independently test power supplies and disassemble them examining the components they went into their construction, this allows you as a consumer to be better informed, for example some power supply units are not in the certified list some of those include cheap PSUs from the likes of ThermalTake such as the ThermalTake Litepower series. There is typically two primary manufacturers (and other less known ones) of PSUs this is GreatWall and CWT. If I do not see a PSU in this tier list I won't touch it with a 40 foot pole. https://www.cybenetics.com/index.php?option=power-supplies but I also use independent reviews load and stress tests are often critical to proper review process involved in power supply evaluation. The big benefit of choosing quality power supplies you'll get a whooping 10 year warranty, some computer shops will not provide you with this level of quality and integrity, as their goal is to install a cheap PSU like a Aywun or Tsunami which WILL come back to bite you, if say a Corsair PSU blows and it's no fault of your own if you provide evidence CORSAIR is known to reimburse your entire PC.

Non-modular

This is often a cheaper form of power supply what a non modular configuration power supply has is wired in cables into the unit as such these tend to lead to a lot of cables left over after building a system which have to be "stuffed" into the case to keep them out of the way this severely impacts both the air flow of a computer to the power supply as well as the ease of maintenance over time.

Partially Modular

Are also a cheaper option however it has some cables soldered or terminated in place meaning some of the cables, not all of them can be removed which can help reduce clutter inside a case, the modular element is usually the ATX 24 pin connector.

Fully Modular

The option I personally always use you may pay a bit more for this option but it reduces the amount of clutter in your PC case because all the cables can be disconnected and the ones which are not required can be put inside their protective case and lastly fully modular units are usually built much more robustly resulting in a power supply that is much easier to maintain long term and far more reliable, as a general rule I purchase top end modular power supplies purely for the sake of myself in terms of building systems as modular PSUs become very important when you start dealing with systems with very little "wiggle" space such as ITX motherboard cases.