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 the BlackDragon 400W 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 the BlackDragon 400W. 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 is not ground breaking, that's for sure, and definitely not even near 86%, at least at the high ambient temperatures we use for testing. The good thing is that the unit managed to deliver its full power, flawlessly, even at close to 50°C ambient, maintaining on the same time quite good voltage regulation (for our standards of course). Since the PSU's max capacity is restricted to 400W we would like to see closer to 1% voltage regulation at +12V, but still an under 2% deviation isn't bad at all. At Cross Load tests the group regulation design that this unit utilizes means bad news/results and exactly this was the case. Finally the PSU has a really quiet operation but surely it doesn't output only 10dBA of noise at 45°C ambient (as Spire claims), at least at one meter distance. The fact is that inside a case it will most likely be the last thing you will hear, unless of course you have Superman's hearing.

Efficiency at Low Loads

In the next tests, we measure the efficiency of the BlackDragon 400W 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.


We conducted only three tests here and skipped the 80W load test since this is the same as the 20% load test that we already ran on the previous section. Efficiency with low loads (although a load of 100W is not so low for the particular unit) is good enough and even at 40W the unit manages to register over 70% efficiency. With 20W more it reaches 76% and with 80W and 100W it surpasses the 80% mark. Overall, for a PSU that doesn't even carry an 80 Plus certification the results here are good.

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.


The 5VSB rail is not so efficient in this unit, especially at lower loads. Only at test#3 the PSU managed to surpass the corresponding threshold, set by ATX spec and with full load efficiency marginally passed 70%.

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).


Although Spire states that this unit is ErP Lot 6 compliant our measurements didn't confirm this. This PSU needs 0.15W more at standby than the maximum power consumption that the aforementioned directive sets, in this mode of operation.