Test Setup

All measurements are performed utilizing ten electronic loads (seven Array 3711A, 300W each, and three Array 3710A, 150W each), which are able to deliver over 2500W of load and are controlled by a custom made software. We also use a Picoscope 3424 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 four more oscilloscopes (Rigol 1052E and VS5042, Stingray DS1M12 and a second Picoscope 3424) and a CEM DT-8852 sound level meter. In this article you will find more details about our equipment and the review methodology we follow. Finally, if the manufacturer states that the maximum operating temperature of the test unit is only 40°C then we try to stay near this temperature, otherwise we crank up the heat inside the hotbox up to 45-50°C.

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) for the same load range.

5VSB Regulation Chart

The following chart shows how the 5VSB rail deals with the load we throw at it.

Efficiency Chart

In this chart you will find the efficiency of ST-1000G at low loads and at loads equal to 20-100% 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 ST-1000G. 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 a high load, 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 minimal.

Efficiency, except with 20% load, is pretty high and remains near 90% even with full load and at 45.3°C ambient. Here we should note that although we stressed the unit pretty hard we didn't activate, even once, the Over Temperature Protection so its trigger point is much higher than the unit's official max operating temperature. Regarding voltage regulation now, +12V is a little above 2%, 5V below 3% and 3.3V is the weak link here since it is close to the 5% limit. The cooling fan was really quiet at low loads and only at the 60% load test, where the ambient was at high levels, it started to make an audible noise which however could not be classified as loud, at least compared to the equivalent noise of other 1000-1200W units we have reviewed in the past. Apparently the new fan does a pretty good job while it keeps noise levels as low as possible.

Efficiency at Low Loads

In the next tests, we measure the efficiency of ST-1000G 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 40, 60, 80 and 100W (for PSUs with over 500W capacity). This is important for scenarios in which a typical office PC is in idle with power saving turned on.

With only 40W load efficiency is low but with mere 20W more it increases near 8%. As you can see from the 60W to 100W load range, efficiency is fairly good for a high capacity unit. The 80% mark is surpassed with 80W, a load level which represents about one 1/12th of the PSU's total capacity.

5VSB Efficiency

ATX spec states that the 5VSB standby supply's efficiency should be as high as possible and recommends 50% or higher efficiency with 100mA load, 60% or higher with 250mA load and 70% or higher with 1A or more load.
We will take four measurements, three at 100 / 250 / 1000 mA and one with the full load that 5VSB rail can handle.

At 5VSB, efficiency is over the respective limits at all tests, however it's not among the best we have ever seen. It peaks at test#4 registering a solid 76%.

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).

Vampire power was a little hard to be measured in this unit since even our highly accurate power meter couldn't get a clear indication, but thanks to our control/monitoring program we managed to get an average reading of 0.14W which of course is very low and 100% compliant with ErP Lot 6 requirements.