Everything You Need to Know About PSU Wattage and Rails

When we think of buying a computer we make sure that all the components are selected from a reputed brand to enjoy a lag free performance. Graphics card, CPU etc. are some of the components that get most attraction while Power supply unit is that component which gets the least attraction.

It is true that we never go by a brand or reputation when it comes to buying a PSU. But, this is the biggest mistake as performance and life of all other components of a computer depend on the Power supply unit. So, the importance of PSU should never be overlooked.

The market is filled with so many good and branded PSU. But, how to pick up the best one. There are several factors that you need to check out before purchasing any power supply unit and those are:

  • Wattage
  • Efficiency
  • Modularity

Wattage is what set a PSU model apart from other models. And this is why it is really important to know about the wattage of a PSU before buying it.

Wattage is nothing but a number that the PSU consume from the wall outlet and then distribute it to the other components. So, when you decide of buying a PSU, first look for the wattage number that is normally written on the box of the power supply unit. Anyways, you will also get to know about the wattage of a PSU from the official website of the brand.

When we normally decide to buy a PSU, first we need to check the total number of electricity consumed by the components of our PC. And then pick up one that has a couple of hundreds more wattage than the required electricity. This is the general rule of thumb.

Power supply units are available in different wattage supply. So, you will get from 300Watt to 1600 watt. It is always suggested to pick up a good PSU which is rated bit higher wattage. If all other components of the PC do not get required supply, they will fail to perform and will cause damage eventually. So, picking up a right and good PSU is highly important.

In case you are unable to find out the required wattage by your PC, you can take help of the online calculator. The internet is filled with so many calculators such as Cool Master’s calculator, OuterVision Extreme Power supply calculator etc. These calculators will help you know which wattage PSU is perfect for you.

Wattage is again of two types, Peak wattage, and continuous wattage. And you should look for a PC that is rated as continuous wattage. Continuous wattage specifies that it is able to deliver the rated wattage continuously. But peak wattage states that this is the maximum power it can deliver. So, always check out if the rated wattage is continuous or peak. And avoid a power supply unit rated as peak.

So, just buying a branded and expensive PSU is not enough rather you need to ensure that is has good continuous wattage.

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#PSU Rails

The next important part about which you should enquire is the PSU rails. PSU rail is nothing but the supplied voltage to the components inside the PSU. The components include motherboard, other circuits, chipset, motors, disk drive logic etc. Normally the Power supply unit includes the three basic rails which are +3.3V, +5V and +12V. These wires are actually called as Rails.

There are several wires that carry the specific voltage to the electric components and all those wires are tied to a single rail in the PSU. The PSU can also use a single rail to carry the specific voltage, but in that case, all the connectors, traces, and terminals have to be really large to handle that big load. And also, the single wire should be thick enough.

Already stated above that a PSU includes three basic rails which are +3.3V, +5V and +12V. And here is the list of components that are powered by the rails.

  • +3.3V- PCI/PCIe card/AGP, Chipset, and some of the DIMMs
  • +5V- PCI/AGP/ISA Cards, low-voltage motors, SIMMs
  • +12V- AGP/PCIe cards, high voltage regulators and motors

Power supply units are available with both single Rails and multiple rails. And you can choose to get any of them. But they have their own pros and cons and we have discussed that in more details here.

Single Rail vs Multi Rail Compatibility Difference: Ever since manufacturers have come out with the multi-rail PSU option, a debate has started and it’s still on. While some says single rails is always best that offer cleanliness and is good for overclocking other says that multi-rails can offer the utmost safety.

Anyways, to understand the difference between single rail and multi-rail you should first know about OCP. OCP is nothing but the overcurrent protection. OCP chip is included in both the PSU models, single rail, and multi-rail but the difference lies somewhere else.

In case of single rail, the +12V power supply is monitored through one single circuit and there is just one OCP chip configured. The chip gets off as soon as the max amp is reached.

But in case of multi-rail PSU, the +12V power source is monitored by multiple OCP chip configured on the PSU. There are more than two monitoring channels and all of them have separate amp rating. These amp ratings are the division of the total output of the PSU.

If we talk about efficiency, both single rail and multi-rail PSU are designed to perform the same way. But when it comes to safety, multi-rail is better than the other one. Safety is not a concern at the low voltage. But as soon as you get to the high wattage units, it becomes really tough to hit the max amp of the PSU on the single rail unit. It will cause overload on the +12V power supply and this may burn all other components of the PSU.

So, it is suggested to pick a multi-rail PSU in case there is the high rate of voltage fluctuation in your area. These are the main things you should look for when buying a PSU as these stuffs indicate how good the PSU is.

“That’s all for now, thanks for sticking with the article, and you know it will always good to let me know about the article, in the comments down below.” 🙂


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