Test Setup

All measurements are performed utilizing a custom designed and built load tester, called Faganas, which is able to stress PSUs up to 1800 Watts. We also use a DS1M12 (Stingray) oscilloscope, a CHY 502 thermometer, a Fluke 175 multimeter and an Instek GPM-8212 power meter. Furthermore, in our setup we have included a wooden box, which along with a heating element is used as a Hot Box. Finally, we have at our disposal nine electronic loads (six Array 3711A, 300W each, and three Array 3710A, 150W each), a Rigol 1052E oscilloscope and a CEM DT-8852 sound level meter. In the near future the electronic loads will form our new test set up, which with the help of our custom built software will have the same capabilities with the, ultra expensive, Chroma ATEs. In this article you will find more details about our equipment and the review methodology we follow.

Voltage Regulation Charts

The following charts show the voltage values of the main rails, recorded over a range from 60W to the maximum specified load, and the deviation (in percent), when compared with the voltage values at 60W load.

Efficiency Chart

In this chart you will find the efficiency of LZP-550 at low loads and at loads equal to 20-120% of PSU’s maximum rated load.

Voltage Regulation and Efficiency Measurements

The first set of tests reveals the stability of voltage rails and the efficiency of LZP-550. The applied load equals to (approximately) 20%, 40%, 50%, 60%, 80% and 100%, of the maximum load that the PSU can handle. In addition, we conduct two more tests. In the first we stress the two minor rails (5V & 3.3V) with the maximum load that our tester can apply to these rails, while the load at +12V is only 2A and in the second test we dial the maximum load that +12V can handle while load at minor rails is minimum.


Wow! Impressive results! Let's start with the unbelievable high efficiency readings. This unit, hands down, is the most efficient we have ever tested! At 40-60% load, efficiency is above 92% and even with full load it reaches 91.5%. You don't see such efficiency readings often, actually even for us it's the first time. Even during the CL1 test, where gold units struggle to pass 80%, the LZP-550 easily registered over 85% efficiency!

As you can see we couldn't resist to overclock the PSU, since the manufacturer states this is possible, and with 647 W load, efficiency is still above 90%. Very impressive without any doubt.

Now let's explain the weird temperature readings. First we must note that probe A that measures the intake temperature is placed close to the cooling fan and the other probe (B) that measures the exhaust temperature is placed on the center of the unit's exhaust.
Up to 60% load, the PSU's fan was not spinning, although the temperature inside the hotbox was too high. Since the fan was not working, heat inside the PSU was dissipated from its top where probe A was located so it is natural to measure much higher temperatures there. The fan started working only when probe A measured 53.5 °C and afterwards the temperature at this area dropped and the temperature that probe B measured increased significantly, since the hot air was pushed to the unit's exhaust grill.

All rails are regulated to change not more than 3% with +12V being really close to 1%. Overall we were very satisfied with the unit's voltage regulation. If Super Flower manages to make an equally performing platform with 1000 W then the competition will have a very hard time to catch up.

Efficiency at Low Loads

In the next tests, we measure the efficiency of LZP-550 at loads much lower than 20% of its maximum rated load (the lowest load that the 80 Plus Standard measures). The loads that we dial are (approximately) 40, 65 and 90W. This is important for scenarios in which a typical office PC is in idle with power saving turned on.


Once more, efficiency is impressive, to say the least. Even with only 42 W load, the PSU registers over 80% efficiency. With 91 W load it is over the Gold requirements.

Power Consumption in Idle & Standby

In the table below you will find the power consumption and the voltage values of all rails (except -12V), when the PSU is in idle mode (On but without any load at its rails) and the power consumption when the PSU is in standby (without any load at 5VSB).


As we expected, vampire power is low, reaching 0.11 W so LZP-550 passes the ErP Lot 6 requirements with flying colors (<1W standby power).