NX-8060 PSU improved: Nexus redux

Power

Nov 16, 2008 by Mike Chin

Product
Nexus NX8060 improved
600W Power Supply
Manufacturer
Nexus
Sample Supplier
End PC Noise
Market Price
~US$125

SPCR doesn't make a practice of revisiting products without a compelling reason. When we reviewed the Nexus NX8060 power supply over a year ago, we summarized....

"The Nexus NX-8060 is a solid, modern, high performance PSU well worthy of consideration. Its acoustic are basically good, but they are bettered by the best."

Why take another look at a reviewed product over a year later? Sometimes, personal conviction is a good reason for action. The folks at End PC Noise, the US/Canada distributor of Nexus, informed us of positive changes to the product. They were convinced we'd like it, and based on their conviction, we decided to take another look, albeit a quick one.

The full details of the NX8060 are available in our original review: It's basically a 600W ATX12V power supply with modular cables and a 120mm fan. Efficiency was found be be fairly good, over 80% through most of the operating range. The electrical performance was good if not exceptional. The acoustic performance was good at low load levels, but its fan ramped up in speed under even a modest load, and fan speed showed a nearly linear response to heat, which is not good for acoustics. The new version's improvement is said to be solely in the acoustics; nothing else has been changed. So we'll focus here solely on noise, and on cooling, which the fan and its controller certainly affects.

The graph below, from the Nexus web site, is also featued on the side of the new retail box for the NX8060. It compares the noise-to-load curve of the new version to that of the original.


This graphic is on the box of the improved version.

Note that the graph tends to exaggerate the difference between the two curves if you just glance at it quickly, because the bottom line is not 0 dBA, but 16 dBA. There are two difrerences between the old and new version curves:

  • The new one starts lower and stays lower.
  • The slope of the rise is visibly flatter up to about 50% load, then it becomes much steeper. This should mean its fan doesn't speed up as quickly as load increase, and the subjective experience will be that it's quieter.

How audible are the differences depicted? Assuming that the sound quality is similar, the 2~3 dBA differences at up to 20% load is probably too close to the ambient noise level of most rooms for it to be significant. But the 5~7 dBA differences at higher loads should be easily audible for almost anyone in a reasonably quiet environment. The change was implemented July 31, 2008, and only the revised version are available in the US and Canada — and probably the rest of the world as well.


No visible changes from the original version.

A quick look at the sample of the new version showed no obvious changes of any kind, outside or inside. As mentioned above, the box differs in that it has the new comparison graph and a couple of stickers that shout "Improved version, even more quiet!" Inside the PSU, there is the same Adda fan as before, model AD1212MB-A71GL, which at 12VDC, is specified by the fan maker to have the following characteristics: 0.33A current draw, 2050 RPM, and airflow of 80.5 CFM. This means the only change is in the fan speed controller.

RETESTING

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.

Acoustic measurements are now performed in our anechoic chamber with ambient level of 11 dBA or lower, and a PC-based spectrum analyzer comprised of SpectraPLUS software with ACO Pacific microphone and M-Audio digital audio interfaces.

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.

Although a full range of load tests were performed, the electrical performance details varied very little from the original sample results (typically within 1% for almost every measured parameter), and they are not presented in full here. We're focused solely on the acoustic and thermal results

Ambient conditions during testing were 21~23°C and 11 dBA. AC input was 122V, 60Hz. The test was conducted in the anechoic chamber with the door open and a house fan aiding in ventilation except when measuring or recording the sound. During load tests for any PSU rated ~400W, the air temperature in the vicinity of the PSU rises by at least 2°C, which is natural and expected in real world use.

ACOUSTICS & COOLING : Nexus NX8060 revised
DC Output (W)
40
65
90
150
200
250
300
450
600
Intake (°C)
24
26
26
29
30
31
31
36
40
Exhaust (°C)
29
30
31
37
39
42
43
55
68
Temp Rise (°C)
5
4
5
8
8
11
12
19
28
Fan Voltage (V)
3.8
4.3
4.3
4.3
4.7
5.1
5.6
7.3
11.1
SPL - dBA@1m
19
20
20
20
22
23
25
32
38

OTHER DATA SUMMARY: Nexus NX8060 original
DC Output (W)
43.0
62.6
89.0
150.4
201.3
249.6
296.1
449.2
599.7
Intake (°C)
25
26
26
29
29
30
31
35
38
Exhaust (°C)
30
31
31
36
39
40
42
51
62
Temp Rise (°C)
5
5
5
7
10
10
11
16
24
Fan Voltage (V)
4.3
4.6
5.0
5.8
6.4
7.1
7.3
10.5
11.5
SPL - dBA@1m
21
24
26
27
29
32
33
38
42

Please note: The original sample is no longer available for testing, and all the comparisons here are based on data compiled during the original review, which was performed in a live room, not the anechoic chamber.

As before, the starting speed of the fan was approximately 4.3V. The measured sound pressure level in the anechoic chamber was just over 18 dBA@1m, a couple dBA lower than what we'd measured with the original sample in the live room. Even though the measured SPL of the new unit is lower than that of the original sample, chances are, they sound very close. When measured in the live room, the revised PSU's minimum SPL was 21 dBA, the same as the original. In any case, we have no real quibble about the claimed loudness difference at minimum load: The original was very quiet, and so is the new version.

More importantlly, the rise in noise as load is increased is significantly slower, as the direct comparison below shows clearly.

Nexus 8060 SPL@1m Comparison: Original vs. Improved
DC Output (W)
40
65
90
150
200
250
300
450
600
Original (dBA)
21
24
26
27
29
32
33
38
42
New (dBA)
19
20
20
20
22
23
25
32
38

At the low end of the above table, the 21 and 24 dBA measurements of the original would be lower by 2~3 dBA if it was done in the anechoic chamber. But as the SPL level approaches 25 dBA, the readings in the anechoic chamber and the live room become much closer, because the PSU dominates as the noise source. For all the readings 26 dBA and up, we can assume that the SPL measurements for the two PSUs were done under the same conditions. There's no question that the new version is much quieter. It's not untill the 300W output level that 25 dBA@1m is reached. Compare that to 26 dBA at 90W with the original model. The new one is much quieter.

Is there is price foir the lower noise? Yes, go back to the two bigger tables above, and you'll see that the revised version has higher temperatures from about 200W on up. The voltage to the fan in the revised unit lags significantly behind the original, which directly reflects the temperature and noise difference. The fan voltage in the revise version nearly catches up at full power, but somehow, the new model still measured 4 dBA quieter. The increased temperature is not bad, and it will be considerably less than measured in our test when used in a PC case with a dedicated or extra outside air intake for the PSU.

The following table compares the SPL-to-load performance of various PSUs tested in the anechoic chamber thus far. The objective data suggests that it's closest to the NesteQ, and this conclusion holds subjectively as well.

Comparison: SPL (dbA@1m) vs. Power Output in Anechoic Chamber
Model
90W
150W
200W
250W
300W
400W
500W
6~700W
Enermax Modu82+ 625*
12
12
14
15
16
26
36
37
Antec Signature 650
15
15
15
18
18
28
36
47
SilverStone DA700
18
18
18
18
23
32
35
41
NesteQ ECS7001
22
22
22
21
23
25
36
37
Nexus 8060 improved
20
20
22
23
25
32
38
42
PCPC Silencer 610
20
24
24
24
24
30
40
50
*Guesstimates based on the Modu82+ 425's idle in the chamber and the Modu82+ 625's load test.

CONCLUSIONS

The NX-8060 improved is a genuine improvement over the original, which it easily bests for low noise. The revised Nexus stays quiet enough to around 300W to be considered a viable option even for demanding silent PC enthusiasts. The use of a case with a separate PSU air intake will still improve acoustics performance, especially with high power rigs, but this is an observation we can make about almost every PSU. The rest of the unit's performance remains very good as before, and self cooling is only slightly affected. It's a good revision.

Our thanks to End PC Noise for the Nexus NX-8060 sample.

* * *

SPCR Articles of Related Interest:
Power Supply Fundamentals
Recommended Power Supplies
SPCR PSU Test Rig V.4
Nexus NX-8060 (original)
Antec Signature 650
SilverStone DA700 power supply
Enermax Modu82+ 625W
NesteQ ECS7001 700W PSU: A Modular Twist

* * *

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