Stress Test: Power Supplies Under Full Load

Epower Silent Engine Xscale 470: Loud At Full Load

This power supply does not live up to its name - the Epower Silent Engine Xscale 470 is loud at full load and does not run efficiently.

The graphic above shows the power supply connections and their length in centimeters. Exemplary connections: Epower Silent Engine Xscale 470.


The power supply unit tested now belongs to the category of candidates, which because of their performance level (470 watts), are very often sold in retail stores. Among its particularities is the ventilation control, which can be adjusted to individual needs by means of a three-level slide switch. The ventilator speed can be adjusted using the settings "auto," "middle" and "low" - during the stress test we are using the setting "auto". This is not necessarily proof of high quality: When the power supply unit was unpacked, two screws that serve to attach the switch became loose. Considering the fact that vibrations occur during operation due to the ventilation, the switch can rapidly develop a mind of its own.

The ePower Silent Engine Xscale-470 on the test platform. The 470-watt power supply is about to undergo 24 hours of stress.

The power supply unit as delivered.

Test Results

The Epower Silent Engine Xscale-470, which above all stands out for its low operating noise, takes top slot. The other candidates so far have all been way too loud, none of which would stand a chance in a workplace environment. An exception was the PSU from Be Quiet which also distinguished itself.

And now the detailed data for the Epower Silent Engine Xscale-470, which completed the test with flying colors:

Power input: 622 watts (212 volts, 2.96 amperes, cosphi 0.99)

Power output: 470 watts (18.2 amperes/3.3 volts, 24.8 amperes/5 volts and twice 11.3 amperes at 12 volts, 20 watts at -5/-12 volts, 5 volt standby)

Full-load efficiency: 75.5% (152 watt power loss heated the air by just under 27° (15°C)).

Noise measurement at full load: 65 dB(A) at 12 centimeters

Besides its specs, the ePower Silent Engine Xscale-470 also looks great, which will likely be a decisive factor among its target group. An interesting feature is the plug on the unit used to power other devices as soon as the PC is switched on. The stability of voltages on the Silent Engine Xscale-470 is another selling point:

12.18 V is on the first 12 V line, 12.04 on the second 12 V line (CPU), 4.76 V on the 5 V line and 3.28 V on the 3.3 V line. The 5 V standby line shines with 4.96 volts.

Our digital storage oscilloscope reveals the spread of voltages: excellent values, which fall within the specifications.

Fantastic values: oscillogram of the Epower Silent Engine Xscale-470.

After no new power supply units were tested over the weekend for safety reasons, the ePower Silent Engine Xscale-470 is starting off today right on time.

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Epower Silent Engine Xscale (470 watts)
Test Phase 1
Test DescriptionLower LimitUpper LimitResult
Increase load from 20% to 100% of nominal load limit94 watts470 wattsPassed
Test Phase 2
Test DescriptionRow 4 - Cell 1 LoadResult
Steady load at 100% nominal loadRow 5 - Cell 1 470 wattsPassed
Test Phase 3
Voltage Stability
Power RailMeasurementMin/Max according to ATX Spec.Result
+ 3.3 V+ 3.28 V+/- 5% (+3.14 to +3.46 V)Passed
+ 5 V+ 4.76 V+/- 5% (+4.76 to +5.25 V)Passed
+ 12 V+ 12.18 V+/- 5% (+11.4 to +12.6 V)Passed
+ 12 V CPU+ 12.04 V+/- 5% (+11.4 to +12.6 V)Passed
+ 5 V Standby+ 4.96 V+/- 5% (+4.76 to +5.25 V)Passed
- 12 V- 11.77 V+/- 10% (-10.8 to -13.2 V)Passed
Power RailMeasurementMin/Max according to ATX Spec.Result
+3.3 V35 mV50 mV (Peak-Peak)Passed
+12 V CPU65 mV120 mV (Peak-Peak)Passed
Further Data
ValueMeasurementRow 20 - Cell 2 Row 20 - Cell 3
Noise Level (max.)65 dB(A)Row 21 - Cell 2 Row 21 - Cell 3
Voltage212 VRow 22 - Cell 2 Row 22 - Cell 3
Current2.96 ARow 23 - Cell 2 Row 23 - Cell 3
Cos Phi (Distorsion of Phase)0.99Row 24 - Cell 2 Row 24 - Cell 3
Efficiency75.5%Row 25 - Cell 2 Row 25 - Cell 3