Sunday, August 21, 2011

How To: Avoid a Terrible PSU

Now, in the basic primer post I made for PSUs and Cases I laid out some solid buying strategies for PSUs.  Basically, use reviews from reputable sources to keep up with information about manufacturer's and their product lines.  This strategy will ensure that you get a quality PSU as long as you're willing to do the research.

But let's say you're on a strict budget.  You don't want to find a quality 500W PSU, you need to find the cheapest quality 500W PSU to buy.  Budget-friendly units usually don't get reviewed, because there's not a lot of good advertising to be had from a line like "Performance is good, and it's cheap as hell."  High-end units get sent to reviewers for free.  Lower-end units they often have to buy themselves, which they try not to do much of (for obvious reasons).  This doesn't mean every low-cost unit is a lemon, but it can be hard to separate the good from the bad.  And picking the good ones comes down to research, building up some knowledge, and buying at the right time, none of which are activities I can distill down into post form for you.

However, I can help you know which PSUs to absolutely avoid.  What's left won't be the cream of the crop, but narrowing the field never hurts.  Without further ado:

  • Read Reviews:  Yeah, yeah, I know what I said.  The truth is that while reviews for low-end PSUs are generally less common, they're far from non-existent, and it's worth at least checking to see if someone has blown up the PSU trying to draw its rated wattage in a test environment.
  • Lack of 80-Plus Certification:  Merely possessing some level of 80-Plus Certification is not an indication of quality.  However, lacking it means that the PSU is either an old design, an inefficient one, or both.  Even if performance is adequate (which is unlikely, under the circumstances) you should avoid such PSUs.
  • Passive PFC:  You can immediately tell if a PSU has Passive PFC by checking the back grill where the socket is located.  If the PSU has a switch to change between 110V and 230V, it's a Passive PFC supply.  By contrast, Active PFC supplies automatically adjusts the power draw of the PSU to conform to the voltage of the outlet you're using.  There's nothing necessarily wrong with Passive PFC from a design standpoint, but it's an old design used primarily because it's cheaper, neither of which are good signs.  Plus, Active PFC is hugely convenient.  To be fair, though, it's difficult to appreciate the convenience until you've moved to Europe and detonated at least one supply.
  • Bullshit Labels:  The PSU's label should show amperage information for all of the rails on the PSU, along with information on the maximum wattage pull for the various rails by themselves and combined.  If it doesn't, it's either a shoddy PSU intentionally mislabeled , or an ancient design, neither of which are good. 
  • Fan Control Knobs:  Unless you're looking at a high-end unit (the Antec TPQ-1200 OC, for example) the presence of fan control knobs likely means that the maker of the PSU you're looking at cheaped the hell out.  The simple fact is that popping a basic fan in a unit along with a knob and a potentiometer is cheaper than the basic thermal monitoring and PWM circuitry necessary to have a fan that auto-adjusts to temperatures.  Quality supplies don't need your input.
  • High 3.3V/5V Numbers:  During the era of the ATX 1.X standard, PSUs were based on the 5V as their main voltage, with the +12V rail powering the CPU and little else.  The ATX 2.0 spec brought the change to +12V as the main rail, and ever since PSU companies have been marginally beefing up their 12V rails, adding the necessary connectors, and marketing their old supplies for use with today's computers.  Fortunately for you, the PSU label will at least tell you the amperages on the rails in question.  When you see 5V or 3.3V amperages higher than +12V amperages, you know you're dealing with an old design that's not worth your money.
  • Price:  Price can clue you in to a PSU being a quality model.  For example, if you're looking at 400W PSU for around $40.00, that shouldn't ring any alarm bells, there are solid supplies at that price around that wattage.  If you're looking at a 600W PSU for that much, that just screams "too good to be true!" all over the place.
  • Don't Use the PSU That Came With Your Case:  Seriously, don't.  Unless you bought something like an Antec Sonata, and know all the information of the retail PSU within (and know it to be a solid model) don't plug that piece of shit in.
That's all I've got for now.  Expect a "Part 2" when/if I come across additional egregious PSU shenanigans.

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