Fortron FSP350-60PN "Aurora" 120mm fan PSU

Power
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TEST RESULTS

Measurements were made at 5 output power levels: 65W, 90W, 150W, and 350W. The PSU was allowed to run for 10~15 minutes at each power level before measurements were recorded. The room temperature was 24C.

A. Load on the PSU

DC LOAD
65W
90W
150W
350W
+12V
24
36
60
156
+5V
20
20
40
110
+3.3V
16.5
26.4
42.3
78
-12V
2.4
3.6
3.6
3.6
-5V
1
2
2
1
+5VSR
1
2
2
1

B. On test bench, in 24C ambient temperature

AC Power
105W
137
217
533
Efficiency
62%
66%
69%
65%
Power Factor
0.62
0.67
0.68
0.71
Fan Voltage (min-max)
3.9-9.7 V
4.1-10.4 V
4.2-10.7 V
9.5-11.2 V
Noise (min-max)
24-42 dBA
24-44 dBA
25-45 dBA
42-45 dBA

The range of the manual fan speed controller is tied to the internal thermistor. When the load and/or temperature is high, the minimum speed available goes up. Note that at 65W output, the minimum fan voltage is 3.9V while at maximum power output, the minimum fan speed is 9.5V. The maximum speed available also goes up, but not as dramatically.

C. In thermal simulation case, over light bulb, no case fan

DC LOAD
65W
90W
150W
350W
AC Power
107W
137
218
533
Efficiency
61%
66%
69%
65%
Light bulb
60W
60W
100W
100W
Fan Voltage (min-max)
4.1-10.7 V
4.2-10.7 V
6.9-10.8 V
10.8-11.3 V
Noise (min-max)
24-42 dBA
24-44 dBA
31-45 dBA
42-45 dBA
Case Temp (min-max)
30C - 28C
30C - 38C
32C - 32C
33C - 32C
Exhaust °C (min-max)
34C - 32C
34C - 32C
37C - 34C
40C - 34C

ANALYSIS

1. VOLTAGE REGULATION was good, within -/+2% on all lines in any combination of loads. The low and high voltage seen on each of the main lines is shown:

  • +12V: 11.85 to 12.42
  • +5V: 4.92 to 5.27
  • +3.3V: 3.34 to 3.41

We have no way of testing line regulation, so AC conditions are steady-state, not dynamic as it would be (potentially) in a real PC. The AC input as measured by Kill-a-Watt is usually within a couple of volts of 120V.

2. EFFICIENCY was modest throughout the power load range and never reached 70% even at high loads. This is below average performance compared to all other PSUs tested by SPCR. One thing to note here is that the power conversion efficiency at 350W is substantially lower than at 150W. This suggests that at 350W output, the PSU is already operating at beyond its maximum; normally, efficiency is highest at or just below maximum output, then falls off beyond.

3. POWER FACTOR was mediocre, ranging from a low of .62 at low loads to a high of .71 at maximum power load. This was expected, given the absence of any power factor correction.

4. FAN VOLTAGE: The fan receives full voltage (10-11V) for a couple of seconds upon startup to ensure that it always starts even if set to the minimum speed, which is a low 3.9V. Although, as mentioned earlier, the fan speed is affected by the internal temperature of the PSU, the minimum speed stays fairly close to 4V except at high power output load. This is particularly true when the PSU is operated on the test bench out of the case.

In the case with the thermal simulation of the light bulb, the first significant change comes at the 150W output level with the 100W bulb. The minimum fan voltage jumps from 4.2V (without external heat) to 6.9V. At this speed the fan is plainly audible, though without any annoying high pitch. At full power, there is virtually no difference between min & max settings of the fan speed dial -- both are very close to the maximum voltage of 11.3V.

5. NOISE was measured at 1 meter from the exhaust grill. The test environment is live, so readings are higher than would be obtained in an anechoic chamber readings. (See explanation in Test Methodology section above.)

Subjectively, the Aurora PSU is quiet. The 120mm fan has a lower pitch sound than most 80mm fans and spins very slowly at minimum. It has some ticking bearing noise, and hums rather than buzzes. It measures and sounds a bit louder than the quietest 80mm fan PSUs tested previously. At the highest speed, wind turbulence noise dominates, along with humming that is higher pitch than at low speed.

The measured noise at minimum is a couple dBA higher than the last PSU tested, the Seasonic Super Silencer 400. It is 4 dBA noisier than a Nexus NX3000. Both of these are 80mm fan models.

6. THERMAL IN-CASE SIMULATION results are quite complex and deserve close attention. Note that the last 4 measured parameters -- fan voltage, noise, case temperature and PSU exhaust temperature -- all have minimum and maximum measurements. This relates to the setting of the manual fan control. The min figures refer to the parameter with the manual fan control at minimum; max is for the same measurement with the manual fan control at maximum.

The temperature of the case was monitored with a thermal probe positioned about 1" below the PSU intake vent and about 1" away from the center. The temperature of the exhaust air from the PSU was measured with a thermal probe positioned about 1/2" away from the center of the PSU exhaust grill panel.

Judging from the upturn in minimum fan speed at the 150W output level with the 100W bulb, in order to minimize noise from a system using this PSU, it is best to keep total system power draw to under 150W. This is not difficult to do with a mid-range system, one with a CPU rated to ~2.5 GHz, no more than a couple of hard drives and a mid-line video card. It is probably possible to run such a system without a case fan, with just the fan in the PSU at minimum and with a quiet fan on the CPU heatsink. Once the load reaches 150W, however, the min fan speed jumps to ~7V and the minimum fan noise reaches above 30 dBA at 1 meter.

7. WHAT ABOUT WITH A CASE FAN?

At the 150W and 350W loads, measurements were repeated with a Panaflo 80mm low speed fan (FBA08A12L1A -- our reference) mounted on the back panel. There was some question about how this case fan would interact with the 120mm fan in the PSU. You will recall this illustration from the first page:

It's the "desirable airflow" pattern shown on the left that was simulated with the case fan blowing out at 12V. At the 150W power load, turning the exhaust case fan on had the immediate effect of increasing the minimum fan voltage from 7V to almost 8V, with a concomitant 2-3 dBA rise in noise. This implies that the temperature seen by the internal PSU thermistor increased.

Why this should have occurred is a bit of a mystery. The total airflow out from the CPU area of the case was increased, so the internal PSU temperature should not have risen; quite the contrary, it should have dropped.

Curiosity and wonder about airflow motivated me to flip the case fan around so that it was blowing outside air into the case. My instinct was that the air being moved out of the case by the 120mm PSU fan at 7V should be fairly close to that blown in by the Panaflo at 12V; perhaps the total airflow through the case would not be much changed from with just the PSU fan working, but there would be the advantage of cooler outside air being blown directly into the hottest area of the case.

The effect of making the back case fan blow in was immediate. Both case and exhaust temperatures dropped by a couple of degrees and there was no increase in the PSU's minimum fan speed.

The results of this back panel case fan flip / flop is tabulated below.

Power Load
150W
350W
Case Fan
Off
Exhaust
Intake
Off
Exhaust
Intake
Fan Voltage*
6.9 V
7.9 V
6.9 V
10.8 V
11.1 V
10.8 V
Noise
31 dBA
34 dBA
31 dBA
42 dBA
43 dBA
42 dBA
Case Temp
32C
33C
29C
33C
33C
32C
Exhaust °C
37C
38C
33C
39C
40C
34C

*The manual fan speed control was set to minimum; it was the internal thermistor than made changes in fan voltage and noise in this test.

It is not clear whether these results would be repeatable in a real system. I encourage owners and users of this Fortron and other similar 120mm fan PSUs to experiment with back case fan directionality and report their findings in the SPCR Forums.

CONCLUSION

The Fortron-Source Aurora 350W ATX12V FSP350-60PN / LED fan PSU is a viable entry to the growing roster of low-noise PC components. It invites experimentation with case airflow. Its strengths include

  • good looks, especially with blue LED fan
  • good stability and voltage regulation
  • good self-cooling
  • good directed airflow design
  • manual fan speed control and reduced noise

The Fortron-Source Aurora 350W does have a few weaknesses:

  • build quality does not seem as high as other Fortron-Source models
  • fan quality could be improved
  • noise could still be lower, especially at higher power loads

Our thanks to Fortron-Source for the Aurora 350W ATX12V FSP350-60PN / LED fan PSU review sample and for their kind support.

* * * * *

Discuss this review in our Forums.



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