Kingwin LZP-1000: Platinum Efficiency at a KiloWatt

Power
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7. TEMPERATURE, COOLING & NOISE

The LZW-1000 uses the same cooling system as the LZW-550. A notice in the product package cautions that the fan does not spin when the unit is first turned on. The following illustration explains its function:

Note that a red switch above the AC input connector on the back panel allows you to switch between ECO Intelligent and "Normal" thermal control. It is in the ECO Intelligent position that the fan does not spin up at turn-on. In position #1, the fan does indeed turn on even with super low load, although its speed does not change until ~500W load is reached.

In ECO mode, it is a "semi-passive" cooling system and the fan comes on only when high temperature is reached. The illustration above states that the turn-on temperature is 65~70°C, and and the fan will stop spinning when the temperature drops to 45~50°C. It is not clear just where in the PSU this temperature is monitored.

Kingwin LZP-1000: Power vs Noise
Load (W)
SPL
(dBA@1m)
Exhaust
22.2
17 / 0
23
41.9
17 / 0
24
65.5
17 / 0
30 / 25
90.7
17 / 0
33 / 26
149.0
17 / 0
33 / 26
199.6
17 / 0
35 / 28
251.2
17 / 0
35 / 28
300.3
17 / 0
36 / 29
400.9
17 / 0
37 / 29
500.5
20
41 / 30
699.9
23
49 / 31
1001.2
25
54 / 33

This is why two SPL numbers are shown in the above table: When set to ECO mode, the fan did not turn on until 500W load, but when set to normal, the fan started at a low 17 dBA@1m SPL. In ECO mode, the absence of electronic noise was striking. This is only the second time I've encountered such a lack of electronic noise from a power supply, and surprisingly, it's happened twice in a row. The previous electronically-silent PSU was the last one I tested, the Seasonic X1050. The noise of the Kingwin LZP-1000 at <500W in ECO mode is similar, well below the 10 dBA noise floor of the anechoic chamber, and inaudible even from under a foot away.

When the fan came on at 500W, it did not stay on continuously. It ran at a speed slightly higher than at normal default, but for only a couple of minutes, then turned off for about five minutes before turning back on again. With the fan running, the relatively cool ambient air quickly cooled the interior of the PSU to 45~50°C, which then triggered the fan to turn off. The measured noise when the fan did come on was about 20 dBA@1m, not quiet enough to go unnoticed (by me, anyway) but smooth and innocuous.

You will notice that there are two temperature numbers at each power level, too. They refer to the temperature at the exhaust vent in normal and ECO mode. When the fan is not running, the heat simply rises up through the fan via convection, so the exhaust vent stays cool. I did record intake temperatures (an inch above the fan) and naturally, it was much higher when the fan was not running, much higher than the exhaust vent temperatures. But when the fan started to run, the heat in the PSU was forced out the exhaust vent, so the temperature naturally shot up. In any case, only at extended full power would I have any concern about whether the PSU keeps itself cool enough. If used in a typical high performance case with a direct air intake for the PSU fan, only extended super loads in very hot weather is likely to risk overheating shutdown in the LZW-1000.

IN THE HOT BOX

The PSU is tested briefly in the hotbox only to check on what happens to noise, fan speed and temperatures when it is used in an outmoded case design which keeps the PSU drawing air from inside the PC case. In this test, roughly 30~50% of the air heated up by the output of the PSU ends up being evacuated through the PSU. This is obviously a lot of heat at full 1000W, and the PSU still has to deal with its own internal heat.

Even in the hot box, the LZP-1000 fan did not turn on except at high test loads. The 20 dBA@1m cited for the 500W 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 70°C, the fan came on and sped up to a higher speed. It stayed at this speed for a good 7~8 minutes before slowing and quieting to 17 dBA@1m, but it did not stop spinning as long as the load was 500W or higher in the hotbox. Even at full power in the hotbox, the noise level never exceeded 25 dBA@1m, and the overall quality of noise was smooth and benign, without tonal peaks.

The main difference compared to outside the hot box was that the fan ran slightly faster (noisier) at ~500W. Outside that power range, there was no appreciable difference in acoustics.

Kingwin LZP-1000 SPL: In Hot Box vs. Out
Power load
90W
150W
200W
250W
300W
400W
500W
700W
1KW
out
<10
<10
<10
<10
<10
<10
17*
23*
25*
in hot box
<10
<10
<10
<10
<10
<10
20*
24*
25*
Measurements are in dBA@1m
* See note in text above.

TOO HOT?

So given the relatively low speed of its fan, is the LZP-1000 is adequately cooled at the higher power levels? Consider that while Seasonic X1050 fan was probably spinning at >2000 RPM at full load, while the LZP-1000 fan seemed to be no higher than perhaps 1200 or 1300 RPM. A complete record of exhaust temperatures were not kept, but the highest exhaust vent temperature at full load was around 70°C, and it would probably climb higher if that load was maintain for a longer period — at most power levels, the test is run for 20~30 minutes, long enough to stabilize temperature most of the time.

  • Does efficiency suffer? Well, yes, in my testing it did drop a bit, but only by about a percentage point, at 700W and 1000W.
  • Does this matter? Perhaps if that power load is often and steadily maintained.
  • Will such modest forced air cooling cause premature heat-related component failure in this PSU? An answer would only be a conjecture, but the 5-year warranty suggests confidence in the product's longevity by Kingwin.

To extend that last comment, my hunch is that Kingwin is making a calculated risk that...

  • Few users will actually use this PSU in a system that demands anything near the full the rated output for long periods. To reach anywhere close to 1000W peaks (never mind sustained loads), my guess is that you'd need the hottest Intel or AMD CPU overclocked to the limit (for perhaps 180W peaks), and at least two of the hottest most power-hungy video cards (for ~600W peaks) all cooled with a massive watercooling system (drawing maybe 60W). The power draw of the motherboard, HDDs, SSDs and other components are not likely to amount to even a hundred watts. This might net >900W peaks in extreme gaming. How many such systems are in actual use out there? Not many. The cost is high and the returns in perceivable gaming performance are diminshed.
  • The cooling required for other components to run stable in such systems will ensure that the PSU only needs to take care of its own heat. No serious gaming case forces the PSU to draw air from inside the case.
  • So, overheating due to actual power load is not much of a risk. Overheating by exposure to extremely hot weather (say >35°C) is also very unlikely: Whoever can afford such a powerful PC can also afford air conditioning. No one wants to sit at a hot gaming terminal with sweaty hands.
  • The cost of few PSUs that might fail early due to the low fan speeds will be more than compensate by increased sales and increased penetration into the silent PC market.

COMPARISONS

The comparison table below shows the SPL versus Power Load on PSUs tested in ambient room temperature, typically 20~24°C. It is most relevant when the PSUs are used in modern cases that provide wide open access to cooler outside air for the PSU cooling fan.

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 (150W~400W), 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 LZP-1000 lands near the very top. The 20 dBA@1m SPL shown for 500W load is higher than actually perceived because it is the highest measured value when the fan is running — but the fan typically runs only about a third of the time at this load (in 22~24°C ambient). When the fan is not running, the noise level is actually lower than those of the fanless models, so it could arguably be placed at the very top of the table.

PSU Noise (dBA@1m) vs. Power in Ambient Room Temperature
Model
90W
150W
200W
250W
300W
400W
500W
6-700W
850W
1KW
Seasonic
X-400/460
Fanless
<10*
<10
<10
<10
<10
<10
<13
n/a
n/a
n/a
Kingwin STR-500 Fanless
<10*
<10
<10
<10
<10
<10
<13
n/a
n/a
n/a
Kingwin Lazer Platinum LZP-550
<10*
<10
<10
<10
<10
<10
16
n/a
n/a
n/a
Kingwin Lazer Platinum LZP-1000
<10*
<10
<10
<10
<10
<10
20
23
24?
25
Seasonic
X-1050
<10*
<10
12
12
13
14
16
26
40
40
Silverstone ST50NF Fanless
11
11
11
11
15
15
16
n/a
n/a
n/a
Enermax Modu/Pro87+ 500
11
11
11
11
11
11
18
n/a
n/a
n/a
Corsair AX850
<10
<10
<10
11~13
12
13
17
24
35
35
Seasonic X-650
<10
<10
<10
<10
<10
16
27
32
n/a
n/a
Nexus NX-5000
11
11
12
12
12.5
14
19
n/a
n/a
n/a
Antec CP-850
12
12
12
12
12
14
20
24
40
40
Enermax Eco80+ 500W
<11
12
12
16
20
23
28
n/a
n/a
n/a
Antec TP-750
12
12
12
14
15
27
31
40
n/a
n/a
Cougar GX-700
15
15
15
17
21
25
35
35
n/a
n/a

The comparison table below shows the SPL versus Power Load data on all the PSUs tested in the hotbox. This is relevant only when the PSU is used in cases with poor ventilation, and forces the PSU to draw air from inside the case.

The Kingwin Lazer Platinum LZP-1000 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, even the just-celebrated Seasonic X1050. Above 500W load, the LZW-1000 has no acoustic comepetition at all. The 25 dBA@1m SPL at 1000W is simply amazing.

PSU Noise (dBA@1m) vs. Power in Hotbox / Anechoic Chamber
Model
90W
150W
200W
250W
300W
400W
500W
6-700W
850W
1KW
Seasonic
X-400/460
Fanless
<10*
<10
<10
<10
<10
<10
<13
n/a
n/a
n/a
Kingwin STR-500 Fanless
<10*
<10
<10
<10
<10
<10
<13
n/a
n/a
n/a
Kingwin Lazer Platinum LZP-1000
<10*
<10
<10
<10
<10
<10
20
23
24?
25
Seasonic
X-1050
<10*
<10
12
12
13
16
16
28
37
40
Kingwin Lazer Platinum LZP-550
<10*
<10
<10
<10
<10
16
22
n/a
n/a
n/a
Silverstone ST50NF Fanless
11
11
11
11
15
15
16
n/a
n/a
n/a
Enermax Modu/Pro87+ 500
11
11
11
11
14
20
23
n/a
n/a
n/a
Corsair AX850
<10
<10
12
15
18
25
35
38
39
n/a
Seasonic X-650
<10
<10
12
14
16
31
31
32
n/a
n/a
Nexus Value 430
11
11
16
18
18
19
n/a
n/a
n/a
n/a
Nexus NX-5000
11
11
12
14
22
24
25
n/a
n/a
n/a
Antec CP-850
12
12
12
14
14
26
40
44
45
n/a
Enermax Eco80+ 500W
<11
12
16
19
26
32
33
n/a
n/a
n/a
Seasonic M12D 850W
14
14
14
14
14
24
37
42
42
n/a
Antec TP-750
12
12
14
14
18
33
40
40
n/a
n/a
Chill Innovation CP-700M
15
15
15
15
17
30
34
34
n/a
n/a
Antec Signature 650
15
15
15
18
18
28
36
47
n/a
n/a
Coolermaster M700W
14
14
18
21
25
27
34
34
n/a
n/a
Cougar GX-700
15
15
18
20
25
32
35
36
n/a
n/a
SilverStone DA700
18
18
18
18
23
32
35
41
n/a
n/a
Nexus RX-8500
14
14
17
22
28
32
32
33
33
n/a
NesteQ ECS7001
22
22
22
21
23
25
36
37
n/a
n/a
PCPC Silencer 610
20
24
24
24
24
30
40
50
n/a
n/a

The green boxes are >30 dBA@1m SPL; ie, too noisy, in our opinion.
*<10= below the ambient of our anechoic chamber; immeasurably low @1m in any environment


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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