Antec SU380 power supply (in NSK2400 case)

PSU 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 SPCR's PSU Test Platform V.3. The testing system is a close simulation of a moderate airflow mid-tower PC optimized for low noise.

Ambient conditions during testing were 22°C and 20 dBA, 120V/60Hz.

ANALYSIS

1. VOLTAGE REGULATION was excellent. Both the +12V and +3.3V rails were within ±1% of their nominal values throughout the test. The +3.3V line did not vary at all until the very last test point, when it rose by 0.01 volt. Those who like to tweak their RAM settings should be very happy with this. The +5V rail was also very well regulated, although it was consistently high throughout the test. Most importantly, though, it stayed high through the test. The total range of variance was 0.06 volts — just a tiny bit more than a 1% variance.

2. EFFICIENCY was also excellent, although it needed a fairly high load before it really shone. Efficiency was well above 80% between 150~300W output. The 84% peak is exceptional for a power supply just bundled with a case. The SU380 actually reached a higher peak efficiency than the Seasonic S12-430, despite the fact that the S12 on its own costs nearly as much as the NSK2400 and the SU380 together.

3. MINIMUM LOAD was actually much lower than indicated on the PSU label. The PSU powered up on our test bench with no load whatsoever. This bodes well for the lower powered rigs that are typical of media PCs. (Keep in mind, however, that shutdown problems in real systems are sometimes caused when the motherboard shuts the PSU down, not just the PSU on its own.)

4. POWER FACTOR - The power factor stayed above 0.99 throughout the testing. Our Extech power meter even reported it as being at the ideal value of 1.00 at a couple of points. Presumably, it never actually reached this value (a practical impossibility), but it's safe to say that the difference was beyond than the precision of our measurement tools.

5. TEMPERATURE & COOLING - Thermally, the SU380 has nothing to worry about. The largest temperature rise between the intake and the exhaust was a measly 4°C, reached just before the fan began to speed up. If anything, the SU380 is overcooled — Antec could probably have gone with a quieter medium or low speed fan without worrying about the internal temperature.

6. FAN, FAN CONTROLLER and NOISE - In fact, that is exactly what Antec should have done, since the minimum noise level was disappointingly high. For those less obsessive about noise, it would still be considered quiet, but given the large number of power supplies with lower base levels it's a shame that a quieter or at least slower speed fan wasn't used. The choice of fan is the one part of the SU380 that isn't top-notch. Obsessive silencers will no doubt find it a perfect candidate for a fan swap.

Even at its lowest level, the fan had a distinctly tonal characteristic that made it more difficult to ignore than the broadband whoosh of airflow. The noise had the beginnings of a whine, though it was low enough in pitch that it came off as more of a growl. The whine quickly became apparent (and noisy) once the fan began to increase in speed.

Fortunately, the fan is very unlikely ever to increase in speed, thanks to the separate thermal zone for the PSU in the NSK2400 case. With the fresh air intake ducts located just a couple inches away from the intake vent of the PSU itself, the intake air temperature would be the same as the external room temperature. In the test setup, the room temperature was 22°C. Given that the internal temperature of the test rig had to reach 32°C and 150W output load before the fan started to ramp up, in practical use, this means the PSU fan will probably rarely, if ever, ramp up in speed. In the NSK2400, the SU380 can be treated as a power supply that runs at a constant 24 dBA@1m, no matter what the load (unless the room temperature exceeds 30°C — too hot to be lounging around near the computer, in our view). With a fan swap, this noise floor could be reduced without endangering the power supply because of the fresh air intake setup of the NSK2400.

MP3 Sound Recordings of Antec SU380 Antec SU380 @ <90W (24 dBA@1m) Antec SU380 @ 150W (25 dBA@1m) There was no need for recordings at higher power levels; it's unlikely that the PSU will ever get that loud in the NSK2400.

Sound Recordings of Comparative PSUs Seasonic S12-430 (Rev. A1) @ 150W (19 dBA/1m) Antec Neo HE 430 @ 150W (21 dBA@1m) Nexus 92mm case fan @ 5V (17 dBA/1m) Reference

HOW TO LISTEN & COMPARE These recordings were made with a high resolution studio quality digital recording system. The microphone was 3" from the edge of the fan frame at a 45° angle, facing the intake side of the fan to avoid direct wind noise. The ambient noise during all recordings was 18 dBA or lower. To set the volume to a realistic level (similar to the original), try playing the Nexus 92 fan reference recording and setting the volume so that it is barely audible. Then don't reset the volume and play the other sound files. Of course, tone controls or other effects should all be turned off or set to neutral. For full details on how to calibrate your sound system to get the most valid listening comparison, please see the yellow text box entitled Listen to the Fans on page four of the article SPCR's Test / Sound Lab: A Short Tour.

CONCLUSION

The SU380 is excellent in every respect except noise, and even that is not a big deal thanks to the fresh air intake setup of the case it is supplied in. Considering the unit comes in the NSK2400 case which has a MRSP of just $99, it's extremely good value for money.

Link to Antec NSK2400 Review

Other SPCR Articles of Related Interest

Antec NeoHE430 power supply
Seasonic Super Silencer 400 power supply

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Antec NSK2400 discussion thread in the SPCR forum.