KitGuru KitGuru.net – Tech News | Hardware News | Hardware Reviews | IOS | Mobile | Gaming | Graphics Cards
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.
We test ambient temperatures at 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 | |
|
120W
|
0.90
|
3.34
|
0.93
|
5.02
|
8.95
|
12.05
|
0.50
|
5.01
|
0.20
|
-12.01
|
|
240W
|
1.62
|
3.34
|
1.63
|
5.02
|
18.45
|
12.05
|
1.00
|
5.01
|
0.20
|
-12.01
|
| 600W |
3.00
|
3.34
|
3.11
|
5.02
|
46.78
|
12.03
|
1.50
|
5.01
|
0.30
|
-12.02
|
| 900W |
4.01
|
3.34
|
4.05
|
5.02
|
70.86
|
12.00
|
2.00
|
5.01
|
0.30
|
-12.01
|
|
1200W
|
5.02
|
3.33
|
5.20
|
5.01
|
94.57
|
11.97
|
2.50
|
5.01
|
0.30
|
-12.02
|
Load regulations is pretty good, with minor fluctuation under full load conditions.
| SilverStone Extreme 1200R | Maximum Load |
| 1426 Watts |
We managed to push this PSU to 1426 Watts before it shut down safely.
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 | |
| 1190W | 4.0 | 3.33 | 3.0 | 5.02 | 88.0 | 11.98 | 0.2 | -12.01 | 0.50 | 5.00 |
| 240W | 19.0 | 3.32 | 22.0 | 5.00 | 2.5 | 12.06 | 0.2 | -12.01 | 0.50 | 5.01 |
The SilverStone Extreme 1200R handled our cross load tests without any issues. When hit with 88A, the +12V rail held at 11.98.
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 | 10 | 10 | 10 | 10 |
| 200W | 13 | 12 | 15 | 12 |
| 400W | 18 | 15 | 20 | 15 |
| 600W | 25 | 15 | 25 | 17 |
| 800W | 26 | 15 | 30 | 20 |
| 1000W | 28 | 20 | 35 | 22 |
| 1200W | 30 | 24 | 42 | 25 |
Ripple suppression falls well within industry rated parameters at full load, although they are higher than we have seen from other units we have tested recently. Not a class leading result but pretty good overall. I would like to see the secondary rails a little lower at higher loads.
|
Efficiency (%)
|
|
|
100W
|
90.3
|
|
200W
|
92.8
|
|
400W
|
93.7
|
|
600W
|
94.3
|
|
800W
|
93.8
|
| 1000W | 93.0 |
| 1200W | 92.0 |
Efficiency is superb, hitting over 94% between 40%-60% load. At full load, efficiency drops to around 92%. This unit is extremely efficient.
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
|
32.6
|
| 800W | 34.1 |
| 1000W | 35.1 |
| 1200W | 35.8 |
This fan doesn't really spin up much at all until later in the power delivery, and at over 800 Watts load it is audible. This all would depend how loud your actual PC is of course, but over 1000 Watt load fan noise levels were actually very well controlled. The fan buzz is not intrusive, and we didn't experience any coil whine either during testing which was good. This could be considered a fairly quiet power supply even when delivering around 1000 Watts of sustained power.
|
Temperature (c)
|
||
|
Intake
|
Exhaust
|
|
|
100W
|
35
|
37
|
|
200W
|
36
|
40
|
|
400W
|
38
|
44
|
|
650W
|
43
|
49
|
|
800W
|
45
|
51
|
| 1000W | 47 | 53 |
| 1200W | 50 | 56 |
Temperatures are well maintained throughout the load range thanks to the high levels of efficiency of the design.
