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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
• 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 | |
|
75W
|
1.21
|
3.36
|
1.18
|
5.04
|
4.87
|
12.18
|
0.50
|
5.03
|
0.20
|
-12.12
|
|
150W
|
2.19
|
3.33
|
2.79
|
5.04
|
9.87
|
12.16
|
1.00
|
5.03
|
0.30
|
-12.10
|
|
375W
|
6.13
|
3.32
|
5.98
|
5.03
|
26.10
|
12.12
|
1.50
|
5.01
|
0.50
|
-12.10
|
| 565W |
10.28
|
3.32
|
10.88
|
5.02
|
38.35
|
12.09
|
2.00
|
5.00
|
0.60
|
-12.08
|
|
750W
|
10.75
|
3.30
|
13.88
|
5.00
|
53.48
|
12.06
|
3.00
|
4.98
|
0.80
|
-12.04
|
A fantastic set of results for the Grand 750W PSU with primary and second outputs all remaining within 1.5% of their target values – excellent.
| ToughPower Grand 750W | Maximum Load |
| 873W |
The PSU managed to hit 873W before shutting down without a problem. It could run at 870W for a reasonably long time and we are glad to report that the overcircuit protection circuitry worked without a hitch.
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 | |
| 734W | 1.0 | 3.33 | 1.0 | 5.06 | 60.0 | 12.04 | 0.2 | -12.08 | 0.50 | 5.01 |
| 154W | 15.0 | 3.29 | 15.0 | 4.98 | 2.0 | 11.98 | 0.2 | -12.12 | 0.50 | 5.00 |
The Thermaltake Grand PSU had no problems with our crossloading tests and even with a 60A load on the 12V output it held steady (load was light on the other outputs). With such an intensive load the voltages can often fluctuate but the Grand really delivers the goods. Obviously this is down to the DC to DC converter design which produces +3.3V and +5V outputs from the +12 rail.
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 Thermaltake unit complied with the ATX standard.
| AC Ripple (mV p-p) | ||||
| DC Load | +3.3V | +5V | +12V | 5VSB |
| 75W | 5 | 5 | 5 | 5 |
| 150W | 5 | 5 | 10 | 5 |
| 375W | 10 | 10 | 15 | 15 |
| 565W | 10 | 15 | 15 | 15 |
| 750W | 15 | 20 | 25 | 15 |
These are fantastic results, in the same class as the Corsair AX supplies we reviewed in the last month. 25mv on the 12V+ is a great figure to see.
|
Efficiency (%)
|
|
|
75W
|
89.1
|
|
150W
|
89.7
|
|
375W
|
92.1
|
|
565W
|
91.6
|
|
750W
|
89.8
|
The efficiency results are fantastic, easily achieving 80 PLUS Gold certification. At 50% load the unit is delivering over 92% efficiency which only drops to 89.8% 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 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
|
21.8
|
|
150W
|
23.2
|
|
375W
|
27.9
|
|
565W
|
31.8
|
| 750W | 36.9 |
The noise reading show that this unit is only really audible when delivering 75%-100% of the total rated power. These are very good results.
|
Temperature (c)
|
||
| Intake | Exhaust | |
|
75W
|
35
|
37 |
|
150W
|
35
|
39 |
|
375W
|
40
|
43 |
|
565W
|
43
|
48 |
| 750W | 45 | 54 |
The 140mm YSTECH flower shaped fan is an impressive beast and keeps temperatures only 9c above ambient intake at full load. Even more impressive is the fact that it doesn't generate a racket when stressed hard.
|
Maximum load
|
Efficiency
|
|
873W
|
85.8
|
We like to rate the units maximum output efficiency, just before it turns off (or blows up as the case may be). We recorded 85.8% in this case which while not realistic conditions for anyone to use, is interesting.
