NesteQ ECS7001 700W PSU: A Modular Twist

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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 V4.1. 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 we test 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 40W and 300W, 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 power draw of several actual systems under idle and worst-case conditions. Our most power-hungry overclocked 130W TDP processor rig with an ATI Radeon X1950XTX-512 graphics card drew ~256W DC peak 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 dual video cards today might draw as much as another 150~200W, but the total should remain under 500W in extrapolations of our real world measurements.

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

Note that the test data shows just two 12V lines. Three separate loads were used: One for the main ATX and drive power output cables, one for the AUX12V connectors, and one for the PCIe 16X power connectors. The PCIe x16 load was equally distributed under 12V1 and 12V2 for convenience. Otherwise, the table (and the page) get too wide to read with any ease.

The ambient temperature was 20°, and the noise level was 19 dBA.

OUTPUT, VOLTAGE REGULATION & EFFICIENCY: NesteQ ECS7001
DC Output Voltage (V) + Current (A)
Total DC Output
AC Input
Calculated Efficiency
+12V1
+12V2
+5V
+3.3V
-12V
+5VSB
11.97
1.01
12.00
1.69
5.24
0.95
3.43
0.97
0.1
0.2
43
55
77.8%
11.96
2.79
11.93
1.68
5.24
0.95
3.42
0.95
0.1
0.2
64
81
78.5%
11.96
2.79
12.05
3.39
5.24
0.98
3.42
1.90
0.1
0.4
89
111
80.6%
12.22
4.77
12.13
4.95
5.14
2.90
3.40
2.64
0.3
0.8
150
177
84.7%
12.18
6.50
12.08
6.68
5.11
3.62
3.38
3.76
0.4
0.8
200
232
86.2%
12.20
8.58
12.11
8.15
5.07
5.42
3.36
4.36
0.2
1.1
253
300
84.5%
12.17
9.42
12.00
11.20
5.06
6.19
3.37
5.13
0.2
1.1
307
364
84.2%
12.00
13.00
12.00
14.1
5.00
8.90
3.30
7.39
0.3
1.7
406
495
82.1%
12.00
18.40
12.00
17.7
5.00
13.8
3.30
9.74
0.4
2.3
551
699
78.8%
12.00
24.00
12.00
24.00
5.00
13.9
3.30
11.30
0.5
3.0
703
923
76.3%
Crossload Test
12.00
18.40
12.00
17.5
5.00
0.95
3.3
0.96
0.1
0.2
440
540
81.5%
+12V Ripple (peak-to-peak): 20mV @ 65W ~ 40mV @ 200W
+5V Ripple (peak-to-peak): 8mV @ 65W ~ 17mV @ 200W
+3.3V Ripple (peak-to-peak): 10mV @ 65W ~ 13mV @ 200W
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: NesteQ ECS7001
DC Output (W)
43
64
90
150
200
253
306
406
551
703
Intake (°C)
22
22
24
25
33
30
30
36
40
50
Exhaust (°C)
28
28
32
33
41
42
42
47
54
63
Temp Rise (°C)
6
6
8
8
8
12
12
11
14
13
Fan Voltage (V)
3.9
3.9
3.9
3.8
4.2
5.3
6.8
10.7
12.3
12.3
SPL (dBA@1m)
22
22
22
22
22
25
26
35
37
37
Power Factor
0.96
0.95
0.98
1.00
0.99
1.00
1.00
1.00
1.00
1.00
AC Power in Standby: 1.2W / 0.05 PF
AC Power with No Load, PSU power On: 7.6W / 0.24 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 This is a measure of AC-to-DC conversion efficiency. The ATX12V Power Supply Design Guide recommends 80% efficiency or better at all output power loads. 80% efficiency means that to deliver 80W DC output, a PSU draws 100W AC input, and 20W is lost as heat within the PSU. Higher efficiency is preferred for reduced energy consumption and cooler operation. The latter allows reduced cooling airflow, which translates to lower noise.

At the 43W load we first applied to the system, efficiency was already at a high 78%. Surprised, we rechecked everything just to be sure. At 90W, the ECS7001 broke 80%, and remained above this all the way up past 400W. Its peak efficiency of 86.2%, which rivals that of the Zalman ZM1000-HP and Enermax Modu82+ 625W, was achieved at 200W. It began dropping around 500W load, falling under 80% by 550W and measured 76.3% at full power. The latter number is probably responsible for this unit not gaining 80 Plus certification. The efficiency curve is somewhat flatter than we've seen in other PSUs, which tend to have relatively poor efficiency at low load, peak at 50~70%, and then drop off again when pushed to their limits.

2. VOLTAGE REGULATION refers to how stable the output voltages are under various load conditions. The ATX12V Power Supply Design Guide calls for the +12, +5V and +3.3V lines to be maintain within ±5%. At all load levels, voltages were well within tolerance, and we were pleased to see that even at high loads, the voltages were spot on.

3. AC RIPPLE refers to unwanted "noise" artifacts in the DC output of a switching power supply. It's usually very high in frequency (in the order of kilohertz or megahertz). The peak-to-peak value is measured. The ATX12V Guide allows up to 120mV (peak-to-peak) of AC ripple on the +12V line and 50mV on the +5V and +3.3V lines. Ripple voltages on the ECS7001 were quite low, well within specifications.

4. POWER FACTOR is ideal when it measures 1.0. In the most practical sense, PF is a measure of how "difficult" it is for the electric utility to deliver the AC power into your power supply. High PF reduces the AC current draw, which reduces stress on the electric wiring in your home (and elsewhere up the line). It also means you can do with a smaller, cheaper UPS backup; they are priced according to their VA (volt-ampere) rating. Power factor was very good for this model, running at no lower than 0.95 at any point during testing.

5. LOW LOAD TESTING revealed no problems starting at very low loads. Our sample had no issue starting up with no load at all.

6. LOW AND 240 VAC PERFORMANCE

The power supply was set to 550W load with 120VAC through the hefty variac in the lab. The variac was then dialed 10V lower every 10 minutes. This is to check the stability of the PSU under brownout conditions where the AC line voltage drops from the 110~120V norm. The ZM1000-HP is rated for operation 115VAC ~ 240VAC ±10%. Most power supplies achieve higher efficiency with higher AC input voltage. SPCR's lab is equipped with a 240VAC line, which was used to check power supply efficiency for the benefit of those who live in 240VAC mains regions.

Low VAC Test: NesteQ ECS7001 @ 550W Output
VAC
AC Power
Efficiency
240V
667W
82.5%
120V
697W
78.9%
110V
702W
78.3%
100V
710W
77.4%
90V
721W
76.3%

The ECS7001 passed the low voltage test without any problems, even as low as 90V. Neither voltage regulation nor ripple changed measurably during the test, and efficiency dropped only marginally. As usual, efficiency improved with 240VAC input.



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