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Athena Power 350W FlexATX Power Supply Review (AP-MFATX35)

Additional technical assistance: Peter McFarland and Jeremy Price.

Correctly testing power supplies is a complex procedure and KitGuru have configured a test bench which can deliver up to a 2,000 watt DC load. Due to public requests we have changed our temperature settings recently – previously we rated with ambient temperatures at 25C, we have increased ambient temperatures by 10c (to 35c) in our environment to greater reflect warmer internal chassis conditions.

We use combinations of the following hardware:
• SunMoon SM-268
•  CSI3710A Programmable DC load (+3.3V and +5V outputs)
•  CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• Extech Power Analyzer
• Extech MultiMaster MM570 digital multimeter
• Extech digital sound level meter
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

DC Output Load Regulation

Combined

DC Load

+3.3V
+5V
+12V
+5VSB
-12V
A
V
A
V
A
V
A
V
A V
88W
3.75
3.33
4.02
4.99
4.21
12.07
0.60
4.99
0.12 -12.04
176W
7.52
3.31
8.03
4.99
8.51
12.02
1.22
4.97
0.25 -12.05
263W
11.26
3.30
12.02
4.98
12.76
11.95
1.86
4.94
0.37 -12.07
350W
15.02
3.26
16.01
4.95
16.98
11.89
2.51
4.91
0.50 -12.11
Athena Power 350W
Maximum Load
354W

Load regulation is pretty good across the output range. We only managed to get an extra 4 Watts from the power supply before it would switch off.

We then used an oscilloscope to measure AC ripple and noise present on the DC outputs. We set the oscilloscope time base to check for AC ripple at both high and low ends of the spectrum.

ATX12V V2.2 specification for DC output ripple and noise is defined in the ATX 12V power supply design guide.

ATX12V Ver 2.2 Noise/Ripple Tolerance
Output
Ripple (mV p-p)
+3.3V
50
+5V
50
+12V1
120
+12V2
120
-12V
120
+5VSB
50

Obviously when measuring AC noise and ripple on the DC outputs the cleaner (less recorded) means we have a better end result. We measured this AC signal amplitude to see how closely the Athena Power unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load +3.3V +5V +12V 5VSB
88W 15 10 20 15
176W 15 15 35 15
263W 20 15 50 20
350W 25 20 60 25

Ripple suppression is well within the guidelines, although it is noticeable across all outputs.

Efficiency (%)
88W
81.56
176W
84.67
263W
82.12
350W
80.23

Efficiency is decent, although it did fall a little short of 80 Plus Bronze specifications.

We take the issue of noise very seriously at KitGuru and this is why we have built a special home brew system as a reference point when we test noise levels of various components. Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.

Today to test the Corsair Power Supply we have taken it into our acoustics room environment and have set our Digital Sound Level Noise Decibel Meter Style 2 one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself.

As this can be a little confusing for people, here are various dBa ratings in with real world situations to help describe the various levels.

KitGuru noise guide
10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refridgerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum

Noise (dBA)
88W
29.8
176W
31.7
263W
33.5
350W
34.8

With such a small fan there are always going to be compromises and at full load, the Athena Power 350W FlexATX is clearly audible. It isn’t realistic to be running this at full load on a continual basis and at 50% load it is audible, but not really noticeable especially in a server style environment.

Temperature (c)
Intake
Exhaust
88W
35
37
176W
38
42
263W
43
48
350W
47
58

Internal temperatures rise to an 11c above ambient variable under full load, which considering the compressed physical layout, is very acceptable.

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