You may also know that the power supply delivers voltage over three “rails:” +3.3V, +5V, and +12. Each component in the system draws the bulk of its power from one of these rails, and you need to monitor how much load is being placed on each. CPUs, for example, use the +5V rail while GPUs depend on the +12V line(s). So simply having a power supply that meets a mainstream enthusiast’s total wattage draw is not sufficient. You need to see how much load is being placed on each rail and confirm that your power supply is up to the task on each front.

A cheap and/or overloaded power supply will exhibit fluctuation on its voltage rails. The ATX specification allows for as much as 5% fluctuation, and you can use a voltmeter to make sure your units are staying within this spec. However, when you get beyond 5%, the quality of power going to the components is compromised. You’ll get voltage spikes, and components will show reduced performance. This is especially true of video cards, which will show artifacting.

Among other reasons, this is why we’ve gravitated toward PC Power & Cooling units over the years. The company, now owned by OCZ, includes test reports with each product shipped, and each report is only generated after the power supply runs through a battery of tests administered by an industrial-class, $100,000 Chroma testing machine. Manufacturers can make power supplies much cheaper if they don’t hold within that 5% range, but it’s like the situation with other components that cut too many corners. Push the product beyond its default specs and you could be asking for heartache. That doesn’t only mean heartache from overclocking. Many users are in homes with old wiring that often let PCs run in brownout voltage conditions while heavy-draw appliances are running elsewhere on the circuit. Cheap PSUs being run outside their optimal comfort zones are far more prone to premature failure.

Unlike so many other high-caliber components in a PC, you might assume that power supplies can’t be overclocked—only that’s not quite true. A few vendors make power supplies with adjustable power rails that let users keep, say, the +12V rail as close as possible to +12.0V as drawing components are overclocked and putting more strain on that rail. This is a true enthusiast feature and not something you’d be likely to see in the mainstream crowd. Being able to knowledgeably demonstrate voltage tuning with a voltmeter under real-world conditions can go a long way to bolster your credibility among prospective high-end buyers


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Even if mainstream buyers don’t need to adjust their rails, they’ll probably want to monitor them, and this is most easily done via an industry standard called Enthusiast Standard Architecture, or ESA.

“ESA is about power supplies, motherboards, cooling, and the chassis,” says Ryan Edwards, product manager of power supplies at OCZ. “It’s essentially a daughter board that’s inserted into the power supply at the point of manufacture, which we do here in our San Diego facility in Carlsbad. That daughter board then does computations, has the firmware, and is able to communicate with the software via connected USB. Part of the fun for enthusiasts is continually changing and tweaking, and if the thresholds are there and are also controllable, I think that’s where the magic happens for them. You can visually see the moves you’re making. Rather than just using motherboard software to get your voltage fluctuation, you actually see it with ESA coming straight from the power supply via the USB and software.”

PC Power & Cooling now has two ESA-compatible models in its Turbo-Cool line. The Turbo-Cool 1200 ESA not only supports the new ESA technology, but it also reveals its specs honestly—1.2kW of sustained power with a 1.3kW peak rate at 50 degrees Celsius. Power supplies tend to degrade in performance as ambient heat increases, so knowing exactly how a unit will perform under adverse real-world conditions is something you should be presenting to clients.

There are ways to blend total power with responsible energy savings. PC Power & Cooling states that its Turbo-Cool 1200 ESA unit is 83% efficient under a 50% load, but this comes as no surprise. 80 PLUS has done excellent work with popularizing power efficiency, but PCP&C was cranking out high-efficiency designs back when the only interested buyers were large industrial organizations. Still, thanks to 80 PLUS’s efforts, having a unit that doesn’t meet the 80% threshold is turning into a liability for some sellers. Enthusiasts want absolute power, but mainstream buyers want savings, and units such as the 1200 ESA offer both.

There are now four certifications offered by 80 PLUS: the original 80 PLUS badge, then bronze, silver, and gold certifications. Each level is judged according to the PSU’s efficiency at three different load levels: 20%, 50%, and 100 percent. Taking the levels in order, a straight 80 PLUS certification only requires 80% efficiency at all three load levels. Bronze specs out at 82%, 85%, and 82 percent. Silver bumps up to 85%, 88%, and 85 percent. Gold sets the bar extremely high at 87%, 90%, and 87 percent.

As with most badge programs, you should be using these certification levels as a marketing tool with prospective buyers. According to 80 PLUS, as of this writing, there are 672 power supplies that meet at least one of the four certifications. A full 583 fall under the basic 80 PLUS category. Eighty line up as bronze winners. Nine qualify for the silver, and none meet the requirements for gold. Clearly, taking top honors is a far harder feat than most outsiders would suspect, but why?

“It’s extremely difficult to manufacture to those exacting standards and maintain any kind of price point that people are likely to pay,” says Eric Ackerson, director of sales and marketing of North America at Antec. “I think there will be some new engineering that helps get us there, but there are also areas where you need to watch for gotchas. For instance, the length of the cables can play a role in whether something is going to pass. With one of the silver-certified products, it recently came into question because it has very short cables, and to actually run it in a real system you have to add extensions to it, but that’s not how it was tested. For testing, you just plug it in as is.”

Some new design elements are simply not power-friendly. To pick one trendy target, modular power supplies are fashionable because they have a strong DIY element, and having the option to implement fewer cables can improve airflow. However, the basic idea of modular power supplies is that you have detachable cables, which means a physical break in the continuity of the wires. There’s an electrical gap that has to be crossed, and with those gaps you get some noise and leak in power at that cable connector. This also results in a serious power efficiency hit.

Looking the other way, there are ways to make power supplies more efficient. One of these is pulse-width modulation (PWM), a feature more commonly found on server power supplies. PWM can control and reduce the amount of power sent to a load. The technology appears in both power supplies and fans, allowing units to be much more efficient in the draw of energy. Fans, for instance, can spin at roughly 10% of their regular speed versus standard control methods that only dip down to 20 to 25 percent. The fan only comes up from that base 10% rate when necessary. PWM power supplies can react in 10 microseconds in contrast to a standard power supply’s 1,000 microseconds. That’s an order of magnitude faster in response time, meaning the PWM power supply’s electronics are watching the heat in the system and reacting much quicker than a standard power supply, dropping noise and making the system more efficient. While still rare in consumer power supplies, you can find this feature on all Antec Signature Series units.

In past articles, we’ve touched on hybrid graphics technologies from both AMD and NVIDIA. Apart from being an excellent value/performance play, there’s an energy savings spin to hybrid that should appeal to those minding their watts. Apart from the fact that an integrated graphics core consumes relatively little power and that power consumption of the discrete GPU can be throttled back or turned off entirely when the chip isn’t needed, there’s another side to hybrid technology when it comes to the power supply.

“It’s very hard to power a Hybrid SLI system because it has very low startup requirements,” says Antec’s Ackerson, referring to NVIDIA’s design. “Part of the graphics subsystem goes kind of into a sleep mode, and the power supply has to be able to operate at a very low power setting to be able to boot it up when it’s in this mode. So far, as of mid-June, very few power supplies can support these conditions, although our Signature Series qualifies. I expect you’re going to see more of this kind of thing as people try to drive down total system power consumption.”

The move to lower power components is a mounting trend, but it can be hard to see today. Even though CPUs are going down in power, high-end GPUs are going up. The net effect is that power draw is still increasing, but there is probably an end in sight. Today’s mainstream enthusiast will probably have all he requires with a 750W to 800W unit.

“I think that 1200W is the highest anyone’s ever going to need,” says OCZ’s Edwards. “I know that may sound like Bill Gates and 64K, but I think we really have topped out there. Us, at the front of the industry, we’re actually looking the opposite direction. I can see us in a year, two years, settling in comfortably with the high end being around 800 watts.”

“Multi-GPU configurations draw a tremendous amount of power,” echoes Antec’s Ackerson. “I think the latest pre-release information on the next generation of NVIDIA GPUs specifies a minimum power supply of 1200 watts. When I spoke to them about two years ago, they were expecting 1500 watts just to support a multi-card configuration. So now the market is dividing into high end and low end and sort of forgetting the middle.”

THE NEW RETRO

To glimpse where that low end is going to be, you might get a clue from the rising number of small form factor designs emerging from Intel, particularly those based on the Mini-ITX form factor. Count in what the Atom processor could accomplish with SFF systems, and you’ve got even more reason to believe that low power is about due for a big comeback. According to Antec, Intel’s target for the mainstream is 250W systems, a number not seen in perhaps 15 years. In those old days, a 250W power supply was little more than a box capable of pumping out 250 watts. Now, we have value-adds such as efficiency ratings, modular cabling, noise output, and other concerns to help resellers give customers a better-tailored solution.

Power supplies are often an afterthought in a system configuration, but the truth is that they deserve nearly equal prominence with the other primary components. In fact, they can be a conversation opener and get buyers considering a whole new direction in their PC decisions.