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7. TEMPERATURE, COOLING & NOISE
A notice on a loose piece of paper in the LZP-550 package cautions that the fan does not spin when the unit is first turned on. On the product web page, a link to ECO Intelligent Thermal Control System (Patent) takes you to the following illustration:
In essence it is a "semi-passive" fan that comes on only when high temperature is reached. The illustration above states that the trigger temperature is 65~70°C, and the fan will stop spinning again once the temperature drops to 45~50°C. (This implies, by the way, that the rated power is valid to 45~50°C.) It is not clear just where in the PSU this temperature is monitored.
What is very clear is that at all but the maximum loads, the fan hardly ever comes on. This is why N/A is indicated for SPL: The noise emitted by the Kingwin LZP-550 during testing was below the 10 dBA noise floor of the anechoic chamber. The fan came on only at full power, and not continuously. It came on initially for about two minutes, then turned off for about five minutes before turning back on again. The relatively cool ambient air quickly cooled the interior of the PSU to 45~50°C. The measured noise when the fan did come on was just 16 dBA@1m, quiet enough to go unnoticed in many environments.
The LZP-550 was not completely noise-free when the fan was not running. At very low loads, with certain combinations of the 5Vsb current, a high pitched noise could be heard clearly from very close distance (under 2-3 feet). As load was increased, this electronic noise faded, but then returned with increased complexity, with several different pitch tones audible at various loads. This noise did not exceed the noise floor of the anechoic chamber, however, and was thus not possible to measure easily. It might be audible to individuals with very sensitive hearing working in an environment with little or no other noise, with this PSU powering a fanless PC in close proximity — say a meter. For 98% of users who employ fans in their PCs, the LZP-550 will rarely be heard.
One complication that arose during testing was the difficulty of measuring temperature. Since the unit was operating in free air, the ambient intake temperature was 21~22°C, but even though the internal temperature had to be rising with increased load, the absence of forced air blowing the heat out toward our sensor mounted at the exhaust grill meant the "exhaust" temperature rose very little. It is probably not a good indication of... anything, in this review.
IN THE HOT BOX
Even when exposed to the heat of the hotbox, the LZP-550 fan did not turn on except at high test loads. The 16 dBA@1m cited for the 400W load is only true part of the time: It stayed off for some 10 minutes at this load before the fan turned on, and it stayed on for only about two minutes. The total time at this load was around 20 minutes, and the fan did not come on again. But after extended operation in the hotbox at 500W load and higher, with the exhaust temperature reaching as high as 69°C, the fan came on and sped up to a higher speed (likely the 1300 RPM maximum it is rated for), where the noise level measured 22 dBA@1m. It stayed at this speed for a good 7~8 minutes before slowing and quieting to 16 dBA@1m, but it did not stop spinning as long as the load was 500W or higher in the hotbox. The overall quality of fan noise even at 22 dBA@1m was smooth and benign, without tonal peaks.
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Kingwin LZP-550 SPL: In Hot Box vs. Out
|
|
Power load
|
90W
|
150W
|
200W
|
250W
|
300W
|
400W
|
500W
|
550W
|
|
out
|
N/A
|
N/A
|
N/A
|
N/A
|
N/A
|
N/A
|
N/A
|
16*
|
|
in hot box
|
N/A
|
N/A
|
N/A
|
N/A
|
N/A
|
16*
|
22
|
22
|
|
Measurements are in dBA@1m
* See note in text above.
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COMPARISONS
The comparison table below shows the SPL versus Power Load data on all the
PSUs tested in the hotbox. It's difficult to rank them, as
the measured SPL varies with power load. The units which are quietest at minimum
load are not always the quietest at midload (100W~300W), which may make them
louder in actual use. Then there's the noise level at 400W and up, which will
determine the quietest PSUs for high power gaming rigs, during actual gaming.
The Kingwin Lazer Platinum LZP-550 acoustics in the hotbox is at the top of the pack, aside from the completely fanless Seasonic X-400 (and X-460). At every load up to its maximum, the unit is quieter than all other tested PSUs.
|
PSU Noise (dBA@1m) vs. Power in Hotbox/Anechoic
Chamber
|
|
Model
|
90W
|
150W
|
200W
|
250W
|
300W
|
400W
|
500W
|
6-700W
|
850W
|
|
Seasonic X-400 Fanless
|
<10*
|
<10
|
<10
|
<10
|
<10
|
<10
|
n/a
|
n/a
|
n/a
|
|
Kingwin Lazer Platinum LZP-550
|
<10*
|
<10
|
<10
|
<10
|
<10
|
16
|
22
|
n/a
|
n/a
|
|
Enermax Modu/Pro87+ 500
|
11
|
11
|
11
|
11
|
14
|
20
|
23
|
n/a
|
n/a
|
|
Corsair AX850
|
<10
|
<10
|
12
|
15
|
18
|
25
|
35
|
38
|
39
|
|
Seasonic X-650
|
<10
|
<10
|
12
|
14
|
16
|
31
|
31
|
32
|
n/a
|
|
Nexus Value 430
|
11
|
11
|
16
|
18
|
18
|
19
|
n/a
|
n/a
|
n/a
|
|
Nexus NX-5000
|
11
|
11
|
12
|
14
|
22
|
24
|
25
|
n/a
|
n/a
|
|
Antec CP-850
|
12
|
12
|
12
|
14
|
14
|
26
|
40
|
44
|
45
|
|
Enermax Eco80+ 500W
|
<11
|
12
|
16
|
19
|
26
|
32
|
33
|
n/a
|
n/a
|
|
Seasonic M12D 850W
|
14
|
14
|
14
|
14
|
14
|
24
|
37
|
42
|
42
|
|
Antec TP-750
|
12
|
12
|
14
|
14
|
18
|
33
|
40
|
40
|
n/a
|
|
Chill Innovation CP-700M
|
15
|
15
|
15
|
15
|
17
|
30
|
34
|
34
|
n/a
|
|
Antec Signature 650
|
15
|
15
|
15
|
18
|
18
|
28
|
36
|
47
|
n/a
|
|
Coolermaster M700W
|
14
|
14
|
18
|
21
|
25
|
27
|
34
|
34
|
n/a
|
|
Cougar GX-700
|
15
|
15
|
18
|
20
|
25
|
32
|
35
|
36
|
n/a
|
|
SilverStone DA700
|
18
|
18
|
18
|
18
|
23
|
32
|
35
|
41
|
n/a
|
|
Nexus RX-8500
|
14
|
14
|
17
|
22
|
28
|
32
|
32
|
33
|
33
|
|
NesteQ ECS7001
|
22
|
22
|
22
|
21
|
23
|
25
|
36
|
37
|
n/a
|
|
PCPC Silencer 610
|
20
|
24
|
24
|
24
|
24
|
30
|
40
|
50
|
n/a
|
The green boxes are >30 dBA@1m SPL.
*<10= below the ambient of our anechoic chamber; immeasurably low
@1m in any environment
The new comparison table below shows the SPL versus Power Load data on
PSUs tested in ambient room temperature, typically 20~24°C. It is most relevant when PSUs are used in cases that provide wide open access to cooler outside air for the PSU cooling fan.
|
PSU Noise (dBA@1m) vs. Power in Ambient Room Temperature
|
|
Model
|
90W
|
150W
|
200W
|
250W
|
300W
|
400W
|
500W
|
6-700W
|
850W
|
|
Kingwin Lazer Platinum LZP-550
|
<10*
|
<10
|
<10
|
<10
|
<10
|
<10
|
16
|
n/a
|
n/a
|
|
Seasonic X-400 Fanless
|
<10*
|
<10
|
<10
|
<10
|
<10
|
<10
|
n/a
|
n/a
|
n/a
|
|
Enermax Modu/Pro87+ 500
|
11
|
11
|
11
|
11
|
11
|
11
|
18
|
n/a
|
n/a
|
|
Corsair AX850
|
<10
|
<10
|
<10
|
11~13
|
12
|
13
|
17
|
24
|
35
|
|
Seasonic X-650
|
<10
|
<10
|
<10
|
<10
|
<10
|
16
|
27
|
32
|
n/a
|
|
Nexus NX-5000
|
11
|
11
|
12
|
12
|
12.5
|
14
|
19
|
n/a
|
n/a
|
|
Antec CP-850
|
12
|
12
|
12
|
12
|
12
|
14
|
20
|
24
|
40
|
|
Enermax Eco80+ 500W
|
<11
|
12
|
12
|
16
|
20
|
23
|
28
|
n/a
|
n/a
|
|
Antec TP-750
|
12
|
12
|
12
|
14
|
15
|
27
|
31
|
40
|
n/a
|
|
Cougar GX-700
|
15
|
15
|
15
|
17
|
21
|
25
|
35
|
35
|
n/a
|
Caution: Please keep in mind that
the data in the above table is specific to the conditions of our test setup.
Change the cooling configuration, the ambient temperature and any number of
other factors, and you could change the point at which the fans start speeding
up, as well as the rate of the rise in speed. The baseline SPL is accurate,
however, probably to within 1 dBA.
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