Stress Test: Power Supplies Under Full Load

Antec True Power 2.0: Mediocre Efficiency

Mediocre efficiency tarnished the showing of the Antec True Power.

The graphic above shows the power supply connections and their length in centimeters. Connections everywhere : in addition to SLI there are also fan connections.

Features And Test Results

Our test participant already started showing problems despite making it through the first 24 hours without a hitch : the Antec True Power 2.0 550W, in the 550 watt class.

Our second test case displayed a couple of issues not seen with the first one. The Antec True Power 2.0 550W (in the 550 watt class of course) withstood the 24 hour stress test. However, it failed to fulfill the requirements set forth by the ATX12V specification, which calls for a maximum fluctuation of 120 mV on the 12 V line. The Antec power supply logged a fluctuation of 140 mV in the first test - definitely too much. The power supply is thus subject to instability.

Input : 745 watts (213 V, 3.7 A, cosphi 0.94)

Output : 550 watts (26 A @ 3.3 V ; 22.8 A @ 5 V ; two times 14.5 A @ 12 V ; 20 W @ -5/-12 V, 5 V standby)

Efficiency under max load : 73.8 percent (195 W dissipation heating the air by roughly 6°C)

Noise measurement at max load : 60 dB(A) at 5 inch (12 cm) distance

In summary, we would point out that the Antec True Power 2.0 550W has a noise level, at 60 dB(A), that is much lower than the PC Power & Cooling Turbo-Cool 510 ATX-PFC for example. For full-load operation, the Antec power supply is really quiet. There were problems, however, observed in maintaining voltage levels on the 12 V line, in violation of the ATX12V specification. In addition, the power supply does not run very efficiently, at a decidedly below-average 73.8 percent ; superior models will register over 80 percent. This power supply costs about $110 in stores - a tidy sum, though typical for its performance class.

Important Update - Antec technicians from Taiwan and the USA visited the Munich THG laboratory for just this purpose. The reason for the 3-hour visit was the divergences we discovered in the ripple test, which were not within spec - although the power supplies did not fail. The technicians from Antec performed new ripple tests on their power supplies together with the THG laboratory engineers. It turned out that the tolerances and high-frequency vibrations with their PSU can lead to varying results in the ripple tests. However, we didn’t observe this phenomenon in any of the other candidates.

Because we determined that the ripple tests can remain entirely within spec in the present models and that the other values were flawless, the Antec devices still earned positive test grades.

Antec technicians and THG lab engineers discuss the technical details involved in measuring the power supplies.

From left to right : Daniel Schuhmann and Bert Toepelt of THG together with the technicians from Antec.

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Antec TruePower 2.0 (550 watts)
Test Phase 1
Test DescriptionLower LimitUpper LimitResult
Increase load from 20% to 100% of nominal load limit110 watts550 wattsPassed
Test Phase 2
Test DescriptionLoadResult
Steady load at 100% nominal load550 wattsPassed
Test Phase 3
Voltage Stability
Power RailMeasurementMin/Max according to ATX Spec.Result
+ 3.3 V+ 3.19 V+/- 5% (+3.14 to +3.46 V)Passed
+ 5 V+ 4.84 V+/- 5% (+4.76 to +5.25 V)Passed
+ 12 V+ 12.06 V+/- 5% (+11.4 to +12.6 V)Passed
+ 12 V CPU+ 11.96 V+/- 5% (+11.4 to +12.6 V)Passed
+ 5 V Standby+ 4.99 V+/- 5% (+4.76 to +5.25 V)Passed
- 12 V- 12.32 V+/- 10% (-10.8 to -13.2 V)Passed
Power RailMeasurementMin/Max according to ATX Spec.Result
+3.3 V40 mV50 mV (Peak-Peak)Passed
+12 V CPU67 mV120 mV (Peak-Peak)Passed
Further Data
Noise Level (max.)60 dB(A)
Voltage213 V
Current3.70 A
Cos Phi (Phasenverschiebung)0.94