Kingwin LZP-1000: Platinum Efficiency at a KiloWatt

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TESTING

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

SPCR's PSU Test Platform V4.1. is the basic setup for the testing. It is a close simulation of a moderate airflow mid-tower PC optimized for low noise. There is one major change: The primary testing is done with the PSU NOT inside the hotbox but atop it, out of the heat path. This is in recognition of several realities that prevail today:

  • In SPCR's test platform, the internal temperature varied proportionately with output load. The tested PSU was subject to this heat, and operating ambient temperature rose with increased load, reaching >40°C and often much higher at full power. This was a realistic simulation of a mid-tower PC case where the PSU is mounted conventionally at the top back portion of the case.
  • The vast majority of "serious" PC cases for the home builder place no longer position the PSU at the top back corner. They put the PSU at the bottom/back corner, mostly out of the path of heat from the other components in the case. This design concept took root with the Antec P180 going back over 5 years, and dominates the DIY case arena. This means the PSU generally has to dissipate only its own heat.

Some time in 2011, we reversed our thermal testing approach: 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 that forces the PSU to draw 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.

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

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. It is true that very elaborate systems with the most power hungry dual video cards today might draw as much as another 150~300W, but the total should remain under 600W.

TEST RESULTS

The ambient temperature was 22~23°, and the ambient noise level was ~10.5 dBA.

Test Results: Kingwin LZP-1000
DC Output (W)
AC Input
(W)
Lost as Heat
(W)
Efficiency %
Power Factor
Exhaust*
°C
SPL* (dBA@1m)
22.2
35
12.8
63.6
0.92
23
17 / 0
41.9
56
14.1
74.9
0.94
24
17 / 0
65.5
81
15.5
80.8
0.98
30 / 25
17 / 0
90.7
105
14.3
86.4
0.99
33 / 26
17 / 0
149.0
166
17.0
89.8
0.99
33 / 26
17 / 0
199.6
211
15.2
92.8
0.99
35 / 28
17 / 0
251.2
265
20.6
92.9
0.99
35 / 28
17 / 0
300.3
322
20.7
93.5
1.00
36 / 29
17 / 0
400.9
426
25.1
94.1
1.00
37 / 29
17 / 0
500.5
533
32.5
93.9
1.00
41 / 30
20
699.9
778
79.1
90.0
1.00
49/31
23
1001.2
1132
130.8
88.4
1.00
54/33
25
Crossload Test
(1A on 5V and 3.3V lines; the rest on 12V line)
700
761
23.4
92%
1.00
49/31
N/A
+12V Ripple (peak-to-peak): <12mV @ <250W ~ 35mV @ 1000W
+5V Ripple (peak-to-peak): <10mV @ <200W ~ 26mV @ 1000W
+3.3V Ripple (peak-to-peak): <10mV @ <200W ~ 26mV @ 1000W
AC Power in Standby: 0.4W
AC Power with No Load, PSU power On: 11W / 0.48 PF
* See text discussion about temperature and noise.

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. It allows reduced cooling airflow, which translates to lower noise. The 80 Plus Platinum standard calls for 90% efficiency at 20% load, 92% efficiency at 50% of rated load, and 89% at full rated load.

At the super low 20W load, efficiency was considerably lower than the LZW-550. Efficiency rose quickly as the load was increased, but remained lower than with the 550W model, and 90% efficiency was reached around 150W, compared to 65W on the smaller model. But as load increased further, the efficiency of the 1000W model reached similarly high levels, actually breaking 94% at 400W. >90% efficiency was maintainee to about 700W, when it began to decline. At full power, our sample missed the required 89% by 0.6%. I don't consider this a significant breach of the specification, as the result is well within the accuracy range of SPCR's load testing system. At such high power levels, I doubt the system has better than ±1.5% accuracy.

The lower efficiency at <150W is to be expected of a 1000W PSU, which is optimized for operation at higher loads. The 94.1% efficiency reached at 400W is the highest measured in any SPCR PSU test thus far. The Seasonic X1050 has somewhat better very low power efficiency, but beyond 100W load, the Kingwin stayed a couple percent higher to full load, which is as it should be. The one anomaly was at 700W load, where the difference between the two KW PSUs fell to just 1.1%.

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 maintained within ±5%.

At all load levels, the critical 12V line was within 3% of 12V. It started high, at 12.37V (+3%) and dropped with increased load to 11.76V (-2%) at full load. The 5V line started a touch high, too, at 5.16V, and went down to 4.89V at full load (+3.2% to -2.2%). 3.3V ranged from 3.39V to 3.32V (+2.7% to dead on). These are good results, not the best we've seen but substantially better than required by the ATX12V design guide.

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 100s of kHz). 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 on all the lines was excellent at all power levels, generally staying under 15mV through the lower half of the power range. Even at 1000W output, the 12V ripple stayed at just 35mV. It's virtually identical to the superb results of the Seasonic X1050 (and the smaller Kingwin LZP-550).

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 or close to 1.0 through most of the loads and no lower than 0.92 even at just 20W load.

5. LOW LOAD TESTING revealed no problems starting at very low loads. Our sample had no issue starting up with no load, either, and the power draw was low. The 0.4W power draw in standby (power switch on but computer off) is excellent.

6. LOW & 240 VAC PERFORMANCE

The power supply was set to 700W load at various AC input voltages. Most full-range input 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 higher mains voltage regions. We also used a hefty variac to check the stability of the PSU under brownout conditions where the AC line voltage drops from the 120V norm.

Various VAC Inputs: Kingwin LZP-1000
VAC
AC Power
DC Output
Efficiency
244V
519W
500W
96.3%
120V
533W
500W
93.9%
100V
542W
500W
91.7%

Efficiency improved to over 96% at the higher voltage. This is much higher than the minimum 94% required at 50% load by the 80 Plus Platinum standard for 230VAC operation, though admittedly, our 244V input is 6% higher than 230VAC. The sample passed the 100VAC minimum input without any issues. Neither voltage regulation nor ripple changed appreciably during these tests.



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