KitGuru KitGuru.net – Tech News | Hardware News | Hardware Reviews | IOS | Mobile | Gaming | Graphics Cards
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. Over the coming months this configuration is likely to be adjusted further and fine tuned.
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
|
||||
|
A
|
V
|
A
|
V
|
A
|
V
|
A
|
V
|
|
|
75W
|
1.20
|
3.35
|
1.16
|
5.08
|
0.2
|
-11.71
|
0.5
|
5.05
|
|
150W
|
2.17
|
3.38
|
2.75
|
5.08
|
0.3
|
-11.69
|
1.0
|
5.02
|
|
375W
|
6.04
|
3.35
|
5.86
|
5.08
|
0.5
|
-11.76
|
1.5
|
4.98
|
|
565W
|
10.05
|
3.33
|
10.65
|
4.99
|
0.6
|
-11.85
|
2.0
|
4.97
|
|
750W
|
10.45
|
3.31
|
13.55
|
4.98
|
0.8
|
-11.85
|
3.0
|
4.88
|
|
DC Output Load Regulation
|
||||||||
|
Combined DC Load
|
+12V1
|
+12V2
|
+12V3
|
+12V4
|
||||
|
A
|
V
|
A
|
V
|
A
|
V
|
A
|
V
|
|
|
75W
|
1.25
|
12.17
|
1.25
|
12.12
|
1.23
|
12.11
|
1.24
|
12.11
|
|
150W
|
2.49
|
12.12
|
2.49
|
12.05
|
2.48
|
12.10
|
2.48
|
12.11
|
|
375W
|
6.47
|
12.08
|
6.53
|
11.95
|
6.47
|
12.07
|
6.49
|
12.01
|
|
565W
|
9.65
|
11.92
|
9.68
|
11.82
|
9.58
|
11.92
|
9.65
|
11.93
|
|
750W
|
13.20
|
11.86
|
13.27
|
11.78
|
13.19
|
11.87
|
13.25
|
11.82
|
The Antec 750W psu is able to deliver solid load regulation on all of the outputs throughout our varied load tests – even when fully loaded, which would be outside normal parameters for the average punter. We were impressed with the primary rail results as well as they fall close to reference 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.
| Combined DC Load | +3.3V | +5V | +12V | -12V | +5VSB | |||||
| A | V | A | V | A | V | A | V | A | V | |
| 725W | 1.0 | 3.36 | 1.0 | 5.07 | 60.0 | 11.75 | 0.2 | -12.00 | 0.5 | 4.96 |
| 200W | 17.8 | 3.29 | 20.0 | 4.91 | 2.0 | 12.18 | 0.2 | -11.88 | 0.5 | 4.94 |
As we had expected the TruePower PSU has no problems with the cross loading stress testing which is helped by the fact it creates the +3.3V and +5V feed using DC to DC converters. All the readings are well within specification and we were happy with the end result.
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 Antec unit complied with the ATX standard.
| AC Ripple (mV p-p) | |||||||
| DC Load | +3.3V | +5V | +12V1 | +12V2 | +12V3 | +12V4 | 5VSB |
| 75W | 10 | 10 | 10 | 10 | 10 | 10 | 15 |
| 150W | 15 | 15 | 15 | 15 | 15 | 15 | 15 |
| 380W | 15 | 15 | 10 | 10 | 10 | 10 | 10 |
| 565W | 15 | 20 | 20 | 20 | 20 | 20 | 20 |
| 750W | 25 | 20 | 24 | 25 | 25 | 20 | 20 |
Again we are more than happy with these results as the ripple suppression is top drawer on all the outputs.
|
Efficiency (%)
|
|
|
100w
|
82.1
|
|
200w
|
87.3
|
|
400w
|
88.5
|
|
575w
|
87.5
|
|
750w
|
86.2
|
The 750W Antec TruePower is clearly a very efficient PSU. The unit peaked at 88.5% around 400W and we never saw it dropping under 80w, even with a minor load of 100W.
|
Noise (dBA)
|
|
|
100w
|
28.5
|
|
200w
|
28.8
|
|
400w
|
29.1
|
|
575w
|
32.1
|
|
750w
|
35.2
|
The noise levels are excellent with the supply being virtually inaudible below 500w. Once 550w load is reached then the fan starts to speed up and it becomes an audible whisper. At full load the noise levels are clearly heard but it never becomes annoying.
|
Exhaust Temperature (c)
|
|
|
100w
|
25.2
|
|
200w
|
25.9
|
|
400w
|
28.5
|
|
575w
|
36.6
|
|
750w
|
44.1
|
This is a very cool running PSU even when loaded at 450W. Over 500W the temperatures start to rise although they are still very good. A full load result of 44.1c is excellent and is one of the better results we have recorded.
