Tagan EasyCon XL 700W: A Tagan at Last

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TESTING

For a fuller understanding of ATX power supplies, please read the reference article Power Supply Fundamentals & Recommended Units. Those who seek source materials can find Intel's various PSU design guides at Form Factors.

For a complete rundown of testing equipment and procedures, please refer to SPCR's PSU Test Platform V.4. The testing system is a close simulation of a moderate airflow mid-tower PC optimized for low noise.

In the test rig, the ambient temperature of the PSU varies proportionately with its output load, which is exactly the way it is in a real PC environment. But there is the added benefit of a high power load tester which allows incremental load testing all the way to full power for any non-industrial PC power supply. Both fan noise and voltage are measured at various standard loads. It is, in general, a very demanding test, as the operating ambient temperature of the PSU often reaches >40°C at full power. This is impossible to achieve with an open test bench setup.

The 120mm fan responsible for "case airflow" is deliberately run at a steady low level (~6-7V) when the system is run at "low" loads. When the test loads become greater, the 120mm fan is turned up to a higher speed, but one that doesn't affect the noise level of the overall system. Anyone who is running a system that draws 400W or more would definitely want more than 20CFM of airflow through their case, and at this point, the noise level of the exhaust fan is typically not the greatest concern.

Great effort has been made to devise as realistic an operating environment for the PSU as possible, but the thermal and noise results obtained here still cannot be considered absolute. There are too many variables in PCs and too many possible combinations of components for any single test environment to provide infallible results. And there is always the bugaboo of sample variance. These results are akin to a resume, a few detailed photographs, and some short sound bites of someone you've never met. You'll probably get a pretty good overall representation, but it is not quite the same as an extended meeting in person.

REAL SYSTEM POWER NEEDS: While our testing loads the PSU to full output in order to verify the manufacturer's claims, real desktop PCs simply do not require anywhere near this level of power. The most pertinent range of DC output power is between about 65W and 250W, because it is the power range where most systems will be working most of the time. To illustrate this point, we conducted system tests to measure the maximum power draw that an actual system can draw under worst-case conditions. Our most power-hungry Intel 670 (P4-3.8) processor rig with nVidia 6800GT video card drew ~214W DC from the power supply under full load — well within the capabilities of any modern power supply. Please follow the link provided above to see the details. It is true that very elaborate systems with the most power hungry video card today could draw as much as another 60~100W, but the total still remains well under 400W in extrapolations of our real world measurements. As for high end dual video card gaming rigs... well, to be realistic, they have no place in silent computing today.

SPCR's high fidelity sound recording system was used to create MP3 sound files of this PSU. As with the setup for recording fans, the position of the mic was 3" from the exhaust vent at a 45° angle, outside the airflow turbulence area. The photo below shows the setup (a different PSU is being recorded). All other noise sources in the room were turned off while making the sound recordings.

INTERPRETING TEMPERATURE DATA

It important to keep in mind that fan speed varies with temperature, not output load. A power supply generates more heat as output increases, but is not the only the only factor that affects fan speed. Ambient temperature and case airflow have almost as much effect. Our test rig represents a challenging thermal situation for a power supply: A large portion of the heat generated inside the case must be exhausted through the power supply, which causes a corresponding increase in fan speed.

When examining thermal data, the most important indicator of cooling efficiency is the difference between intake and exhaust. Because the heat generated in the PSU loader by the output of the PSU is always the same for a given power level, the intake temperature should be roughly the same between different tests. The only external variable is the ambient room temperature. The temperature of the exhaust air from the PSU is affected by several factors:

  • Intake temperature (determined by ambient temperature and power output level)
  • Efficiency of the PSU (how much heat it generates while producing the required output)
  • The effectiveness of the PSU's cooling system, which is comprised of:
    • Overall mechanical and airflow design
    • Size, shape and overall surface area of heatsinks
    • Fan(s) and fan speed control circuit

The thermal rise in the power supply is really the only indicator we have about all of the above. This is why the intake temperature is important: It represents the ambient temperature around the power supply itself. Subtracting the intake temperature from the exhaust temperature gives a reasonable gauge of the effectiveness of the power supply's cooling system. This is the only temperature number that is comparable between different reviews, as it is unaffected by the ambient temperature.

TEST RESULTS

Ambient conditions during testing were 21°C and 19 dBA. AC input was 122V, 60Hz. Note that our testing equipment is set up to accommodate only two +12V rails, and the +12V1 and +12V2 columns in the data table below refer to the loads as measured on our test bench. In addition, it's far from clear which rails power which connections. For this reason, the exact load balance across the various +12V rails is unknown.

OUTPUT & EFFICIENCY: Tagan EasyCon XL 700W
DC Output Voltage (V) + Current (A)
Total DC Output
AC Input
Calculated Efficiency
+12V1
+12V2
+5V
+3.3V
-12V
+5VSB
12.15
0.97
12.13
1.71
5.09
0.98
3.39
0.97
0.0
0.2
41.8
70
59.6%
12.15
1.91
12.13
1.70
5.09
1.96
3.39
1.90
0.1
0.3
62.9
95
66.0%
12.15
2.87
12.10
3.23
5.08
1.95
3.39
0.98
0.1
0.4
90.7
127
71.6%
12.15
4.72
12.09
4.88
5.07
3.81
3.40
3.74
0.1
0.6
152.6
195
78.2%
12.15
6.56
12.08
6.31
5.07
4.58
3.38
4.63
0.1
0.9
200.5
251
79.9%
12.14
7.69
12.07
7.97
5.07
6.49
3.38
5.47
0.2
1.1
248.8
309
80.5%
12.14
4.72
12.08
14.07
5.07
7.18
3.38
8.59
0.2
1.3
301.6
374
80.6%
12.15
7.58
12.08
18.77
5.06
7.86
3.38
8.55
0.3
1.7
399.6
495
80.7%
12.14
10.38
12.05
21.94
5.05
11.30
3.37
11.13
0.4
2.1
500.3
631
79.3%
12.14
13.10
12.02
25.04
5.03
14.44
3.37
14.51
0.4
2.6
599.3
779
76.9%
12.16
12.25
12.10
32.01
5.05
16.86
3.38
16.8
0.5
3.0
699.2
947
73.8%
Crossload Test
12.14
11.39
12.07
31.87
5.07
1.96
3.38
1.91
0.2
0.2
542.7
688
78.9%
+12V Ripple: 18.2 mV @ 150W ~ 24.9 mV @ 700W
+5V Ripple: 4.1 mV @ 40W ~ 11.1 mV @ 700W
+3.3V Ripple: 6.9 mV @ 40W ~ 13.6 mV @ 700W
NOTE: The current and voltage for -12V and +5VSB lines is not measured but based on switch settings of the DBS-2100 PS Loader. It is a tiny portion of the total, and potential errors arising from inaccuracies on these lines is <1W.

OTHER DATA SUMMARY: Tagan EasyCon XL 700W
DC Output (W)
41.8
62.9
90.7
152.6
200.5
248.8
301.6
399.6
500.3
599.3
699.2
Intake Temp (°C)
20
21
23
25
26
26
28
29
32
35
36
Exhaust Temp (°C)
26
28
30
34
36
39
45
49
56
65
72
Temp Rise (°C)
6
7
7
9
10
13
17
20
24
30
36
Fan Voltage (V)
5.3
5.4
5.6
6.8
7.6
8.3
10.4
11.1
11.9
12.1
12.1
SPL (dBA@1m)
29
30
30
36
40
41
45
45
45
45
45
Power Factor
1.00
0.97
0.97
0.97
0.97
0.99
0.99
1.00
1.00
1.00
1.00
AC Power in Standby: 0.9W / 0.16 PF
AC Power with No Load, PSU power On: 14.2W / 0.83 PF
NOTE: The ambient room temperature during testing can vary a few degrees from review to review. Please take this into account when comparing PSU test data.

ANALYSIS

1. EFFICIENCY was good, but it didn't live up to the expectations that we have of a power supply that appears to be 80-Plus certified. If fact, it's peak efficiency barely broke 80% — a long way from the 84% peak efficiency that was measured in the 80-Plus report.

Efficiency at lower loads was actually quite poor, perhaps because the second transformer added some power overhead that most power supplies don't have to deal with (see low-load performance below).

We can only speculate why our test sample did not meet expectations, but there are three possibilities that come to mind:

  1. The sample tested in the 80-Plus test was a special 80-Plus version that will be released in addition to the regular version. This would explain why Tagan does not list 80-Plus compliance anywhere in their marketing material.
  2. Our stringent thermal test conditions caused efficiency to drop (especially at full load). 80-Plus tests are conducted in a uniform thermal environment, regardless of load.
  3. It's possible that our test did a poor job of balancing the load between the two transformers, leading to one or the other being loaded above or below the optimal point on its efficiency curve. As a result, the total efficiency would end up being lower, as the two transformers would hit their peaks at different times instead of simultaneously.

2. VOLTAGE REGULATION was probably the best we've ever seen. All voltage lines remained within ±3% of nominal (+12V and +5V were within 2%), but what was really impressive was how little fluctuation there was. The largest fluctuation was ~1.1% on the +5V line, with a high of 5.09V @ 65W to a low of 5.03V @ 600W. All other lines were regulated to within 1%.

3. RIPPLE

Ripple was far below the tolerance limits of 120 mV (+12V) and 50 mV (+3.3V & +5V), even under stressful conditions. Even in the worst cases, ripple never exceeded about a quarter of the maximum limit.


This bizarrely irregular waveform was produced on the +12V line at 200W output.

4. POWER FACTOR was excellent thanks to the active power factor correction circuit, staying very close to the theoretical maximum of 1.0.

5. LOW LOAD PERFORMANCE

There's no question that the EasyCon XL is a beefy power supply, so it's probably a little unfair to fault it for poor low load performance, but we're going to do so anyway. The 15W consumed with no load on the power supply was almost double what other power supplies have achieved, and it probably contributed to the poor low-end efficiency.

6. LOW AC VOLTAGE PERFORMANCE

BROWNOUT RESILIENCE: Tagan EasyCon XL
Input AC Voltage
AC Current
AC Wattage
Efficiency
+12V1
+5V
+3.3V
120V
5.56
675
78.7%
12.14
5.05
3.37
110V
6.16
684
77.7%
12.14
5.05
3.37
100V
6.83
695
76.5%
12.14
5.05
3.37
90V
7.85
713
74.6%
12.14
5.05
3.37

Doing the low AC voltage test with 700W flowing through the system was an exciting experience, punctuated by occasional sparks and flashes from within the bright orange variac that we used to reduce the voltage. Despite these signs that we were playing with powerful forces beyond our control (wheeee!), the Tagan handled the fluctuation like a champ. The only visible change on the output side was a slight increase (<1 mV) in +12V ripple.



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