Antec Neo HE 430 power supply

TEST RESULTS

For a fuller understanding of ATX power supplies, please read the reference article Power Supply Fundamentals & Recommended Units. Those who seek source materials can find Intel's various PSU design guides at Form Factors.

For a complete rundown of testing equipment and procedures, please refer to the article SPCR's PSU Test Platform V.3. It is a close simulation of a moderate airflow mid-tower PC optimized for low noise, recently revised and updated for improved accuracy and reliability.

In the test rig, the ambient temperature of the PSU varies proportionately with its output load, which is exactly the way it is in a real PC environment. But there is the added benefit of a high power load tester which allows incremental load testing all the way to full power for any non-industrial PC power supply. Both fan noise and voltage are measured at various standard loads. It is, in general, a very demanding test, as the operating ambient temperature of the PSU often reaches >40°C at full power. This is impossible to achieve with an open test bench setup.

Great effort has been made to devise as realistic an operating environment for the PSU as possible, but the thermal and noise results obtained here still cannot be considered absolute. There are too many variables in PCs and too many possible combinations of components for any single test environment to provide infallible results. And there is always the bugaboo of sample variance. These results are akin to a resume, a few detailed photographs, and some short sound bites of someone you've never met. You'll probably get a pretty good overall representation, but it is not quite the same as an extended meeting in person.

REAL SYSTEM POWER NEEDS: While our testing loads the PSU to full output (even >600W!) in order to verify the manufacturer's claims, real desktop PCs simply do not require anywhere near this level of power. The most pertinent range of DC output power is between about 65W and 250W, because it is the power range where most systems will be working most of the time. To illustrate this point, we conducted system tests to measure the maximum power draw that an actual system can draw under worst-case conditions. Our most powerful Intel 670 (P4-3.8) processor rig with nVidia 6800GT vidcard drew ~214W DC from the power supply under full load — well within the capabilities of any modern power supply. Please follow the link provided above to see the details. It is true that very elaborate systems with SLI could draw as much as another 100W, perhaps more, but the total still remains well under 400W in extrapolations of our real world measurements.

SPCR's high fidelity sound recording system was used to create MP3 sound files of this PSU. As with the setup for recording fans, the position of the mic was 3" from the exhaust vent at a 45° angle, outside the airflow turbulence area. The photo below shows the setup (a different PSU is being recorded). All other noise sources in the room were turned off while making the sound recordings.

INTERPRETING TEMPERATURE DATA

It important to keep in mind that fan speed varies with temperature, not output load. A power supply generates more heat as output increases, but is not the only factor that affects fan speed. Ambient temperature and case airflow have almost as much effect. Our test rig represents a challenging thermal situation for a power supply: A large portion of the heat generated inside the case must be exhausted through the power supply, which causes a corresponding increase in PSU fan speed.

When examining thermal data, the most important indicator of cooling efficiency is the difference between intake and exhaust. Because the heat generated in the PSU loader by the output of the PSU is always the same for a given power level, the intake temperature should be roughly the same between different tests. The only external variable is the ambient room temperature. The temperature of the exhaust air from the PSU is affected by several factors:

• Intake temperature (determined by ambient temperature and power output level)
• Efficiency of the PSU (how much heat it generates while producing the required output)
• The effectiveness of the PSU's cooling system, which is comprised of:
  • Overall mechanical and airflow design
  • Size, shape and overall surface area of heatsinks
  • Fan(s) and fan speed control circuit

The thermal rise in the power supply is really the only indicator we have about all of the above. This is why the intake temperature is important: It represents the ambient temperature around the power supply itself. Subtracting the intake temperature from the exhaust temperature gives a reasonable gauge of the effectiveness of the power supply's cooling system. This is the only temperature number that is comparable between different reviews, as it is unaffected by the ambient temperature.

On to the test results...

Ambient conditions during testing were 21°C and 19 dBA, with an input of 120 VAC / 60 Hz measured at the AC outlet.

The output table below summarizes the output voltage and current for each output level tested. Note that even though three +12V rails are specified for the Neo HE, we only measured +12V output in two locations: The main ATX connector (+12V1) and the +12V Auxiliary connector (+12V2).

ANALYSIS

1. VOLTAGE REGULATION stayed within the specified ±3% rating. At full load our +12V2 measurement was just shy of being 3% low. Note that even though all the +12V lines are regulated together, the two +12V measurements are not quite identical. This reflects the different points of measurement that our test system requires. Strictly speaking, neither of the two measurements is "correct", but we judge voltage regulation based on the worse of the two measurements. In the lower output range where the PSU will be most heavily used, all voltages were consistently about 1% below the nominal voltage. This is very good performance.

2. EFFICIENCY was a little disappointing for a model that claims to be high efficiency. The meassured efficiency peak of 79% is three percentage points off the 82% claimed for 115VAC input. Because our methodology for testing efficiency has just been revised, we do not yet have a large database of efficiency data to compare our results to, but preliminary testing has turned up at number of power supplies that peak above 80% efficiency. It would not be correct to say that the Neo HE is inefficient, merely that it not as efficient as Antec claims, and it is not quite in the top tier when it comes to efficiency.

3. POWER FACTOR was excellent thanks to the active power factor correction circuit. Power factor quickly approached the theoretical maximum of 1.0, and never dropped below 0.94.

4. TEMPERATURE AND COOLING

The temperature rise across the Neo HE was quite small, typically around 5-6°C, and it changed very little with load. This suggests that the fan controller did a good job of keeping the internals of the power supply cool without over-cooling.

5. FAN, FAN CONTROLLER and NOISE

At lower output levels, the Neo HE is one of the quietest power supplies we've heard. The reported 20 dBA@1m was actually so close to the ambient level in our lab that it is difficult to judge whether it would measure less in a quieter room. The fan is both quiet and smooth at this level.

The fan is an Adda AD0812MB-A71GL, a "medium speed" ball bearing fan designed specifically for low noise. This is a surprising departure from their usual fan source, Dynatron. The 80M Adda fan comes from the same family as the 120mm fan in the quiet Seasonic S12-500/600 power supplies. Thanks to the handy reference chart on Adda's web site, we determined that "MB" indicates a medium speed, ball bearing fan and "GL" indicates a low noise design. Antec claims that this fan was the result of extensive development work with Adda that only recently bore fruit. Antec's product development manager says this is a very special fan.

There is substance to these claims. The fan maintains its smooth character even when it is running close to full speed, although it inevitably develops some motor whine as it spins faster. As expected, it is far from quiet at full speed, measuring 40 dBA@1m at the maximum 10.8V supplied by the fan controller.

A smooth, quiet fan is a good starting point. What makes a truly quiet power supply is a quiet fan paired with an intelligent fan speed controller that balances noise and cooling well. There are very few examples of such power supplies. The Neo HE 430 is one.

The fan voltage did not begin to increase until about 31°C intake temperature, reached at around 150W output. Changes in fan speed were gradual and could not be easily heard even when sudden changes in heat or output occurred. The power supply became easily audible at around 36°C and became loud around 39°C — at 250W output, which is unlikely to be reached except in hot, power-hungry systems.

In an intelligently designed system of medium to high power, the Neo HE 430 is unlikely to rise much above its low default noise level. Forcing the fan to ramp up to the point where it becomes noisy would require an extremely powerful, hot-running system, with at least one powerful VGA card. Given that very few powerful VGA cards are quiet, it is unlikely that the Neo HE 430 will be the main source of noise in any system.