Every Consumers Guide to Building A Reliable Desktop 2

Building A Reliable And Practical Desktop Computer System (part 2)


This section deals with computer power supplies.

It is the most essential aspect to consider when building your own computer system.  Every component of the computer relies on power to run. A bad power supply is the “Achilles Heels” of the computer system.  

Components can get damaged by unstable power levels.  The lifespan of a component may be greatly compromised or severely shortened if it doesn’t get the proper level of power supplied while some components won’t power up at all.  With some components, it might even cause data corruption if not properly powered.

In some cases, an underpowered system causes issues that will indirectly affect your system and make problems very hard to find or troubleshoot.  In the worst case, your system will just shut down inadvertently or will not function at all or.

  • The role and importance of power supplies
  • Understanding Rails
  • Wattage and rules of thumb
  • Power supply modularity
  • Conclusion and rules of thumb

Power To The People (And The Machines)

Computers put power in the hands of people.

For that to happen, computers need builders to select the proper power supply to put in a new system that is about to be built.

The computer power supply is another component that a lot of people tend to skim to save money.  

Don’t buy the cheapest power supply you can find.

Why?  Like the computer case, this was another lesson that I learned the hard way over the years.

A good power supply will not burn up or break down within 2 to 3 years, sometimes even sooner.  

Buying cheap power supplies, just like cheap computer cases, get costly in the long run.  Cheap power supplies break down more often and the cost adds up over time.

In addition, a cheap power supply is not able to supply stable and consistent levels of power to all the other components.  This can cause system instability and indirectly cause malfunctions that can be very hard to trace sometimes. Problems caused by insufficient or unstable power can lead to a lot of frustration.  Sometimes the symptoms are rather cryptic and many hours are wasted on fixing issues about something that could be entirely avoided by getting the proper power supply for the job.

Power Supply Instability

When power levels are unstable, it causes unnecessary damage to computer components and shortens component life.  None of these things will help you build a stable desktop computer system.

On average, I would suggest using a power supply of no less than 500 watts at least.  I personally purchase power supplies rated between 600 watts and 750 watts. A power supply rated between 600 to 750 watts will satisfy most builds with enough power to spare for additional hard drives and an entry to the intermediate level discrete graphics card – for those wishing to install dedicated video display card.

Some builders like to build very power-efficient systems that are eco-friendly in terms of power consumption and would be the exception in this case.  Using the lowest wattage power supply that is still able to power all your components properly would be your goal and priority.

Power supplies 500 watts and above will usually supply enough power to drive the hardware in your custom built PC in a safe and stable manner.

Common Ratings For Power Supplies

Power supplies come in different ratings.  


  • The basic 80 Plus rating means that the PSU is rated for at least 80% efficiency at 20% load, 50% load, and 100% load.
  • The 80 Plus Bronze rating means that the PSU is rated for at least 82% efficiency at 20% load, 85% at 50% load, and 82% at 100% load.
  • The 80 Plus Silver rating means that the PSU is rated for at least 85% efficiency at 20% load, 88% at 50% load, and 85% at 100% load.
  • The 80 Plus Gold rating means that the PSU is rated for at least 87% efficiency at 20% load, 90% at 50% load, and 87% at 100% load.
  • The 80 Plus Platinum(bet you didn’t know there was a Platinum) rating means that the PSU is rated for at least 90% efficiency at 20% load, 92% at 50% load, and 89% at 100% load.

To make things less complicated, think of it this way.

Basic 80 Plus is the LOWEST rated power supply and the 80 Plus Platinum is the HIGHEST rated power supply.  

The purpose of the rating IS NOT really to indicate the power supply’s construction quality.  The rating’s purpose is really to point out a measure related to a power supply’s EFFICIENCY at converting power from the outlet for the computer to use.  It does, as a consequence, require that the power supply is built with good quality components and a sound design.

For the average user trying to build a computer, a power supply rated at 80 Plus Bronze will prove to be adequate for most regular system builds.  The 80 Plus Bronze also happens to be the power supply that is also very well priced for the average system build budget.

If you are trying to build is really power demanding, the sweet spot will be somewhere between the 80 Plus Silver and 80 Plus Gold.  You will also have to do some math to figure out whether the 80 Plus Silver or Gold is better for you.

For most regular folks looking to build a general purpose mainstream computer system, the 80 Plus Bronze is more than enough.

What In The Rails Is Going On Here??

Nope.  It is not about trains.  It is also not about walking down the stairs safely with your hands on the rails.

This section about power supplies was written to satisfy the few more curious minds that are not satisfied with less headache-inducing answers.  

I wanted to briefly talk about this feature of power supplies to simplify it and maybe even demystify all the confusion and routine disputes about rails and power supplies.

When it comes to rails, there are just two kinds: single rail power supplies and multiple rails power supplies.

Rails are basically traces or connections or paths on the circuit board housing the electronics of the power supply components.  Each rail comes with its respective overcurrent trigger (when too much power drawn that could cause things to burn) that shuts down the power supply unit to prevent damage or potential hazard.  

A single rail power supply has all the power supplied from a single path or trace out to all the components.  It has overcurrent protection to monitor and shut down the power supply to prevent damage when an overload takes place for the one single rail.

The two different rail designs both have safety in mind at the top of the list but are handled differently.

Are multiple rails better or are we better off with single rails?  The answer is not very clear-cut.

All The Fuss About Multiple Rails

Single rail power supplies will not easily shut down at the slightest sign of going overcurrent (when the power load is too high).  The catch is that the overload safety might not trigger until it is too late – potentially causing a fire, for instance.

Multiple rails might do a better job sensing power overloads.  However, they do have a tendency to shut down the whole power supply even if only one of the rails detects a slight overload.  

Multiple rails are more sensitive in this aspect.  This is both good and bad. Why? Imagine if one of the components kept drawing more power and triggering your power supply to shut down constantly.  This would not make your system very stable and good to use either.

In light of these facts, it seems very complicated to pick a power based on single or multiple rails, right?

There is good news for you.  Unless your power requirements are very strict and very high to start with (as in high-performance gaming systems), your choice of single or multiple rails power supply will have little or no effect on system performance or compromise safety.  

You can pick either one and you will be just fine.  If you follow this guide for building your system, your custom build computer will never draw that much power to affect the choice of either rail system.

If you are still obsessed about a power supply and its featured rail system at purchase, the tips below will give you some idea on making a good purchasing decision.

From the description on the box, make sure that the 12v rails that power your most critical components (graphics cards and CPUs) have the proper amperage.

A general rule, 12v rails should be able to deliver at least 18 amps minimum to be on the safe side.  If you are using an entry to intermediate level gaming graphics cards, make sure the 12v rails deliver at least 24 amps.  

If you are building a system using dual graphics cards (usually a very powerful gaming rig), then make sure the 12v rails deliver at least 34 amps. CPU and gaming graphics cards consume the most power out of all the components.

In summary, for the regular user, multiple rails or single rails will not matter that much.  Power supplies today are built as multiple rails one way or another. The choice of a regular system build doesn’t have to be complicated.  Once again, either multiple rails or single rail power supplies will do just fine.

The single rail power supply of today is usually built out of multiple rails internally.  If you are building a general purpose computer system and not using very demanding graphics cards, then you will not have to worry about multiple or single rails.  

If you do run into a situation where you are going to run more powerful graphics card or when setting up multiple gaming graphics cards, just follow the few rules about amperage on the 12v rails and you should be fine.                                                   

For wattage, look for continuous wattage numbers and not peak wattage values that are printed on the box.  

Continuous wattage means whether the power supply can constantly provide (continuous wattage) that many watts while in use compared to whether the power supply produces a wattage UP TO (peak wattage) a certain power level.

For most of the systems I have built, I have never had to use any power supplies lower than 500 watts or higher than 750 watts.  

Once again, I aim to build computers for mainstream use and I do not have to worry too much about rails and strict power requirements except following the few general rules I have already presented so far.

Since our mission for this guide is to guide consumers to build general purpose computers for mainstream use, you will probably not have to worry about all the complications of rails and amperage for most of the builds you make.

Choose your power supply based on features you need and do buy a name brand.  The power supply is a very central component that is often overlooked just like the computer case.  Your build will fail miserably if you do not have a good power supply at its foundation.

In summary, keep in mind the following when you are considering a power supply – all the big ideas to help guide you.

  • For the most part, a mainstream system will do fine with a power supply within 500 watts to maybe 750 watts range.  If you need more watts, ask why and have reasons to justify that
  • If you are powering a system with more demanding components (gaming graphics card or dual graphics cards) make sure that the 12v rail delivers 34 amps
  • Continuous wattage delivered is more crucial than peak wattage delivered.  Make sure you read the power specs that comes printed on the package for the power supply
  • Single rail and multiple rails might make a difference when you are building higher performance systems, but will not matter that much, in general, if you are building a general mainstream desktop system for general use.
  • Buy a brand name power supply.
  • Do not try to save on power supplies.  If the power supply cannot handle the load created by all the components, your computer will not do well.
  • When it comes to power supply rating, most mainstream general use builds will do fine with a power supply rated at the 80 plus bronze.  The 80 basic rating is O.K, but I rather we stay on 80 plus to be safe. The price difference is negligible.

Modularity Like Legos

The title is very suggestive.  If you like Legos you understand modularity well.  In building a computer, a modular power supply can really help clear the clutter of cables.

With Legos, you take small blocks of plastic and put the pieces together to make a larger system or object – a block at a time.

Modular Power supplies follow the same philosophy.  Instead of bundling a bunch of different connectors on just a few long wires and hope there are enough connectors to power everything, the power supply provides different outlets that you can choose to plug each wire to power each component separately.

Modular Power Supplies are very helpful when you are not that great with cable management or when your case does not have too many cable management features.

All the cables you need can be individually plugged into the power supply to the computer component of your choice.  It becomes a one-to-one connection.

You only plug and use as many cables you need to connect all the components.  Extra connections that are not needed can be unplugged and taken away from the power supply to reduce clutter.  The result is a system that has better airflow and fewer cables to block fans or the heat that is trying to come out of the system.

All the rails providing all the different voltages need for powering your computer components are there.  Each individual cable plugs into a particular connection.

In a non-modular power supply, all of the power connections are connected to cables and unneeded wires or connectors need to be tucked away if they are not used or is too long.

Here is a list of power supplies to get you started

Cooler Master (these ones below is rated 80 + bronze which are will do well for the average computer user).  These are also modular!

550w,  650w,  750w

EVGA ( more 80 + bronze rated power supplies)

500w, 600w

Here is an 80 + basic from Thermaltake


Building a more eco-friendly and energy friendly computer?


Fancy an 80 + Gold rated or Platinum rated power supply for something more demanding?

800w(gold)  800w(platinum)

There you go.  Are you ready for the next part on CPU and memory?

Read on for some general rules to follow when you are thinking about purchasing your next CPU and memory matching set.


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