Overview

Since late august of 2002, a flood of new features have started to crop up in the world of power supplies.  What complicates matters even more is that between the 5 or 6 high end supplies on the market, almost all of them incorporate a different type of technological “advantage”.  During this review, we spent a lot of time researching each supply to see which of these new technologies is the most promising.  Although some features may appear strikingly similar to each other, keep in mind that like cases, switching power supplies do not have many manufacturers.  Most power supplies on the market are actually manufactured by Topower, Delta or Channel Well (CWT).  

For those of you who do not know how modern switching power supplies work, let us provide a brief explanation.  When electricity enters the power supply, it is in the form of AC or alternating current.  Essentially, the polarity (direction) of the current alternates back and forth, around 60 times a second.  The advantage of AC current is that it can easily be transformed from high voltage to low voltage.  This way, power can be transported hundreds of miles over high voltage lines, and then transformed to lower voltages for household use.  Unfortunately, AC current is not acceptable for the fine motors and circuitry in computer components, thus, the current must be switched to DC. 

Through a process of rectification, the alternating current is broken down into its positive and negative currents and thus the DC current is produced.  Since this current is not quite suitable for use yet, it is then pulsed in a transformer to reduce the voltage.  Finally, the output is filtered, and sent to various parts of the computer.  This process is what gives PSU’s the title of switching power supplies.  We will talk more about the switching process when we analyze PFC. 

Unfortunately, the conversion from AC to DC does not come free.  As the max DC outputs of these power supplies continue to rise, so does their creation of heat.  In order for power supplies to effectively produce the most efficient DC, they must be kept reasonably cool. Vantec’s solution to this problem comes in the form of two unique solutions; aluminum construction and a 3 way fan array (2 intake, 1 rear exhaust).  The other 3 samples we had simply used two powerful (but quiet) fans to move as much air as possible.  Some of the other new technologies we have seen are truly innovative leaps and bounds over existing technology.  Others are just carefully thought out optimizations. 

Some of these new technologies we will be discussing in this article.  Below is a brief description of some of the newest features on PSU’s in the market today:

Aluminum Construction – We have seen cases use this material before, now power supplies are mimicking its success and cooling advantages.
Silent Fans – Almost every PSU on the market is pushing *silent* fans.  Most PSU’s insist on using fans under 34dbA.
Mesh ATX cable sheath – Virtually all quality PSU’s have decided to switch to this simple and clever approach to reducing tangles in the main ATX cable.
Power Correction Factor – The mysterious PFC is beginning to show up in several PSU’s including Enermax and ThermalTake.
Thermal/Manual fan control – Most power supplies are also shipping with adjustable fan controls to reduce the drone of the fans when it’s not needed. 
Additional Fans – Vantec and other manufacturers are adding additional fans on the PSU in order to improve airflow through the PSU and the case.
Copper Component Shielding – Some PSU’s are attempting to reduce EMI by shielding components with copper.
Dedicated Line Circuitry – Antec is among the first to add dedicated circuitry for it’s +3.3V and +5V DC lines to provide unshared max wattage outputs.
Motherboard Monitoring – With the exception of Vantec, the other three supplies we will be analyzing today have 3-pin monitoring connections to allow fan monitoring on the motherboard.

Index Antec Truepower
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  • Sir Fredrick - Tuesday, January 11, 2005 - link

    I would have really liked to see them compare the current draw from the wall, to see how the PSUs compare in terms of energy efficiency. Reply
  • Anonymous User - Friday, August 22, 2003 - link

    Switching power supply means the unit can be switched between American 60 Hz, 120 v, and European 50 Hz, 240 v input. Reply
  • Jeff7 - Monday, June 18, 2012 - link

    "Switching power supply" refers to precisely what the article says. The "switch" refers to the manner in which the incoming power is handled, not to a physical component on the unit.
    Plenty of switching power supplies, also called SMPS (switch-mode power supplies), are available without any switches.
    Beside me is a switcher supply that accepts 100-240VAC and puts out 12VDC. There are no switches on it.
    Some of the circuitry I work with uses small switcher supplies, which take 12-36VDC and put out a solid 12VDC output.
    I also work with boosters, which are a kind of switching power supply topology that's capable of putting out a higher voltage than what comes in. These particular ones can take 12VDC and put out about 17.5VDC.
    And, I'm looking at a power supply for integration into a new product, and it can handle anything from 85-264VAC at 47-440Hz. Again, no switches on it.

    Some of the older or cheaper switcher supplies *do* indeed have the selector switch on them to let them accommodate different voltages. But that's not what makes them "switching" power supplies. The name "switch" being the same is simply a coincidence.
    Reply
  • Anonymous User - Friday, August 08, 2003 - link

    :):):):):):):):) Reply
  • Anonymous User - Thursday, August 07, 2003 - link

    Reply
  • Anonymous User - Thursday, August 07, 2003 - link

    PFC, power factor correction, is not just about noise. The square wave shape of current draw of non PFC corrected supplies adds a significant 3rd order harmonics element to the line. This usally is gets diverted by the impedance of power company transformers to flowing in the Neutral line of the power system, which in the past carried almost no current. This nuetral line was installed at a SMALLER size than the mains. There have been buildings burned up in Europe, (which has an older infrastructure) because of this. Also, drawing higher peaks instead of sinusoidal current is less efficient and adds more loss the the wires and transformers, shortening their life and adding more pollution to the world, (ie. more power has to be generated to make up the loss, resulting in more smokestack emissions). Reply

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