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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
• SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa)
• 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 | |
|
75W
|
1.08
|
3.35
|
1.45
|
5.07
|
4.90
|
12.07
|
0.50
|
5.02
|
0.20
|
-12.05
|
|
150W
|
2.09
|
3.34
|
2.99
|
5.06
|
10.07
|
12.04
|
0.50
|
5.00
|
0.30
|
-12.05
|
|
300W
|
4.27
|
3.33
|
6.02
|
5.04
|
20.61
|
12.00
|
1.00
|
4.98
|
0.30
|
-12.07
|
| 450W |
6.56
|
3.31
|
8.51
|
5.02
|
31.84
|
11.94
|
1.50
|
4.98 |
0.30
|
-12.07
|
|
600W
|
9.95
|
3.28
|
12.22
|
4.98
|
41.82
|
11.87
|
2.50
|
4.98
|
0.30
|
-12.08
|
The Corsair CX600M delivers decent results with our regulation test, holding within 3 percent.
| Corsair CX600M | Maximum Load |
| 622W |
We managed to get 622W out of the power supply before it would shut down ….safely, we might add.
Next we want to try Cross Loading. This basically means loads which are not balanced. If a PC for instance needs 500W on the +12V outputs but something like 30W via the combined 3.3V and +5V outputs then the voltage regulation can fluctuate badly.
| Cross Load Testing | +3.3V | +5V | +12V | -12V | +5VSB | |||||
| A | V | A | V | A | V | A | V | A | V | |
| 590W | 5.0 | 3.33 | 5.0 | 5.05 | 46.0 | 11.84 | 0.2 | -12.07 | 0.50 | 5.00 |
| 145W | 12.0 | 3.27 | 15.0 | 4.94 | 2.0 | 12.06 | 0.2 | -12.05 | 0.50 | 4.99 |
The Corsair unit handled the intensive Cross load tests rather well, although there was some droop on both +3.3V and +12V rails. Nothing we would consider concerning or long term problematic however.
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 unit complied with the ATX standard.
| AC Ripple (mV p-p) | ||||
| DC Load | +3.3V | +5V | +12V | 5VSB |
| 75W | 15 | 10 | 25 | 15 |
| 150W | 20 | 15 | 35 | 15 |
| 300W | 20 | 20 | 40 | 20 |
| 450W | 25 | 25 | 45 | 25 |
| 600W | 30 | 25 | 50 | 25 |
Ripple results are within the tolerance guidelines set out by the industry. The +3.3V Output peaks at 30 mV and the +5V output peaks at 25mV. +12V output peaks at 50mV, well within the rated parameters.
|
Efficiency (%)
|
|
|
75W
|
81.12
|
|
150W
|
82.96
|
|
300W
|
86.22
|
|
450W
|
84.64
|
|
600W
|
82.53
|
Efficiency is very good, considering the modest 80 Plus Bronze certification the unit is rated at. It peaks at just over 86% at 50% percent load, and this drops to around 82.5% at full load. No concerns here.
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 Power Supply we have taken it into our acoustics room environment and have set our SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa) 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)
|
|
|
75W
|
<28.0
|
|
150W
|
<28.0
|
|
300W
|
29.7
|
|
450W
|
31.5
|
| 600W | 35.1 |
The power supply is quiet, even when hit with around 400W of load. The fan starts to actively spin up in the last 15% of output becoming audible, although never that intrusive – it really isn't practical to be running at a constant 550W+ output from a 600W unit anyway.
We noted earlier that Corsair are using the Yate Loon D12SM-12 fan, an excellent choice as the testing indicates.
|
Temperature (c)
|
||
|
Intake
|
Exhaust
|
|
|
75W
|
35
|
39
|
|
150W
|
37
|
44
|
|
300W
|
39
|
48
|
|
450W
|
44
|
53
|
|
600W
|
47
|
59
|
The large fan works well, holding decent ambient temperatures, even under heavy load. At full load temperatures rise to 12c above ambient.
|
Maximum load
|
Efficiency
|
|
622W
|
81.5
|
At 622W the Corsair PSU rates at 81.5% efficiency. This is not a viable ‘real world’ situation, but its interesting nonetheless.
