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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 – 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
We test with the +12V in single rail mode.
|
DC Output Load Regulation
|
||||||||||
|
Combined DC Load |
+3.3V
|
+5V
|
+12V
|
+5VSB
|
-12V | |||||
|
A
|
V
|
A
|
V
|
A
|
V
|
A
|
V
|
A | V | |
|
100W
|
1.53
|
3.35
|
1.77
|
5.07
|
6.66
|
12.07
|
0.50
|
5.03
|
0.20
|
-12.03
|
|
200W
|
3.13
|
3.35
|
3.50
|
5.07
|
13.50
|
12.07
|
1.00
|
5.02
|
0.20
|
-12.04
|
| 400W |
6.42
|
3.35
|
7.04
|
5.07
|
27.50
|
12.06
|
1.50
|
5.02
|
0.30
|
-12.04
|
| 600W |
9.81
|
3.34
|
10.75
|
5.06
|
41.70
|
12.05
|
2.00
|
5.02
|
0.30
|
-12.05
|
|
800W
|
13.25
|
3.33
|
14.55
|
5.05
|
56.40
|
12.03
|
2.50
|
5.01
|
0.50
|
-12.05
|
| 1000W | 16.55 | 3.33 | 15.67 | 5.03 | 71.40 | 11.97 | 3.00 | 5.00 | 0.60 | -12.05 |
Load regulation is excellent, holding with 1.5%.
| Corsair RMx Series 1000W |
Maximum Load |
| 1103W |
We managed to get another 103 watts from the power supply before the protection circuitry kicked in. Great results.
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 | |
| 885W | 2.0 | 3.34 | 2.0 | 5.05 | 72.0 | 11.97 | 0.2 | -12.05 | 0.50 | 5.03 |
| 240W | 20.0 | 3.32 | 24.0 | 5.01 | 2.0 | 12.06 | 0.2 | -12.05 | 0.50 | 5.04 |
The unit passes the cross loading test with both +3.3V and +5V rails holding steady. The +12V rail droops a little when hit with 72A, but it is well within what we would expect.
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 |
| 100W | 5 | 5 | 5 | 5 |
| 200W | 5 | 5 | 5 | 5 |
| 400W | 5 | 5 | 10 | 5 |
| 600W | 10 | 5 | 15 | 5 |
| 800W | 10 | 10 | 15 | 5 |
| 1000W | 10 | 10 | 15 | 10 |
Ripple suppression is excellent. All rails hold well within the industry rated tolerance levels. +3.3V and +5V peak at 10mV. +12V peaks at 15mV at 100% load.
|
Efficiency (%)
|
|
|
100W
|
87.32
|
|
200W
|
88.65
|
|
300W
|
90.23
|
|
500W
|
92.19
|
|
800W
|
91.69
|
| 1000W | 90.81 |
Overall efficiency results are very strong indeed, peaking at around 92% between a 500 watt and 600 watt load. This drops to almost 91% efficiency at full load.
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 Refrigerator
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)
|
|
|
100W
|
<28.0
|
|
200W
|
<28.0
|
|
400W
|
<28.0
|
|
600W
|
29.9
|
| 800W | 33.4 |
| 1000W | 34.8 |
The NR135L 135mm fan doesn't spin until around 400-430 watts are demanded from the unit. In the last 250 watts of power, it gradually spins up until full load, when it is generating around 35dBa of noise. This fan is clearly spinning faster in the RM1000x than it does in the RMx 750W at full load.
|
Temperature (c)
|
||
|
Intake
|
Exhaust
|
|
|
100W
|
35
|
38
|
|
200W
|
35
|
44
|
|
400W
|
37
|
46
|
|
650W
|
43
|
49
|
|
800W
|
45
|
54
|
| 1000W | 47 | 61 |
Temperatures are well controlled throughout the power range.
|
Maximum load
|
Efficiency
|
|
1105W
|
89.91
|
Pushing the power supply above its rated limits generates an efficiency level of around 89.91%. This is not a viable ‘real world’ situation, but its interesting nonetheless.
