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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 deilver 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
• SunMoon SM-268
• 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
|
-12V
|
+5VSB
|
|||||
|
A
|
V
|
A
|
V
|
A
|
V
|
A
|
V
|
A
|
V
|
|
|
100W
|
1.68
|
3.34
|
1.77
|
5.09
|
6.65
|
12.05
|
0.2
|
-11.71
|
0.5
|
5.10
|
|
200W
|
2.77
|
3.33
|
3.54
|
5.09
|
13.71
|
12.03
|
0.3
|
-11.69
|
1.0
|
5.07
|
|
380W
|
7.72
|
3.29
|
7.17
|
5.06
|
25.95
|
12.00
|
0.3
|
-11.72
|
1.5
|
5.02
|
|
580W
|
9.40
|
3.27
|
7.81
|
5.03
|
42.18
|
11.95
|
0.5
|
-11.72
|
2.0
|
4.97
|
|
775W
|
4.70
|
3.29
|
3.99
|
5.06
|
61.95
|
11.80
|
0.6
|
-11.74
|
2.5
|
4.9
|
The table above shows the results for the Toughpower XT. The five +12V outputs were combined to four DC pre-programmable loads. Load regulation across the range is extremely impressive, even when pushed to 775W.
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
|
|
|
715W
|
1.01
|
3.32
|
1.0
|
5.03
|
60.0
|
11.80
|
0.2
|
-11.74
|
0.5
|
5.05
|
|
160W
|
15.0
|
3.23
|
17.0
|
4.99
|
2.0
|
12.05
|
0.2
|
-11.90
|
0.5
|
5.06
|
The Thermaltake Toughpower XT PSU coped with our cross loading test and produced a stellar set of results. We placed a really intense load on the +12V output and a small load on the other outputs. Frequently with this kind of load a PSU will gave worrying voltage results, but these are very good indeed.
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 | +12v1 | 5VSB |
|
100W
|
4
|
2
|
13
|
15
|
|
200W
|
5
|
2
|
21
|
16
|
|
380W
|
5
|
3
|
29
|
18
|
|
580W
|
5
|
3
|
35
|
20
|
|
775W
|
6
|
4
|
39
|
21
|
The XT 775W once again delivered a fantastic set of suppression figures across the AC ripple scale, particularly on the +12V rail.
|
Efficiency (%)
|
|
|
100w
|
84.1
|
|
200w
|
89.7
|
|
380w
|
90.5
|
|
582w
|
90.1
|
|
775w
|
87.4
|
There is no questioning the efficiency of the XT 775W Power Supply with results over 90% throughout the 360w-600w range. The PSU actually is into the 80 Plus Silver category but Thermaltake have marketed the unit as 80 Plus Bronze, which is rather modest of them.
|
Noise (dBA)
|
|
|
100w
|
31.7
|
|
200w
|
34.2
|
|
380w
|
34.3
|
|
582w
|
35.2
|
|
775w
|
43.1
|
The noise levels are excellent with the supply being virtually inaudible below 450w. Once 500w 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
|
24.8
|
|
200w
|
26.7
|
|
380w
|
33.2
|
|
582w
|
38.4
|
|
775w
|
47.1
|
Only when the unit hits over 600W load does the temperature reach 40c. Thermaltake have managed to get a good balance of noise v thermal dynamics throughout the range, it is not practical for a 775w power supply to be running close to 100% load on a sustained basis.
