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 TTBPK20G at low loads and at loads equal to 20-100% of PSU's maximum rated load.

Fan RPM & Delta Temperature

In the following chart the cooling fan's speed (RPMs) along with the delta difference between input and output temperature are illustrated. The following results were obtained at 40C°-50C° ambient.

Voltage Regulation and Efficiency Measurements

The first set of tests reveals the stability of voltage rails and the efficiency of TTBPK20G. 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 high but unfortunately not as high as we would expected from a Gold efficiency unit. Also PF is low and only with 50% load it manages to surpass 0.9. Voltage regulation at +12V is decent but we would like to see a deviation closer to 2% rather than 3%. At 5V, voltage regulation is fairly good and at 3.3V somehow disappointing. Apparently the 3.3V rail is the weak chain of this unit, at least in the voltage regulation section. The PSU had no problem whatsoever delivering its full power at very high temperatures but the cooling fan made its presence well felt and most likely will be annoyingly loud for most of the users.

In the following table you will find the data we gathered through the iPower Meter.


As you can see the iPower meter's readings cannot be characterized as accurate, especially at higher loads. All voltage readings are way off and the same applies to efficiency, too. Watt readings are close to the real ones up to 50-60% load but afterwards the deviation is much bigger. Surprisingly the Amp readings on the minor rails are accurate and the +12V rail, up to a certain load level, provides also accurate Amp readings. All in all, don't trust the shown voltage and efficiency readings but you can use the total Watt readings and the Amps drawn from each rail. Finally, during full load and CL2 tests the temperature reading on the iPower meter exceeded 70°C and an alarm triggered. However the PSU didn't shutdown and we were able to continue our tests without any problems. Once the temperature fell below 70°C the alarm stopped.

Efficiency at Low Loads

In the next tests, we measure the efficiency of TTBPK20G 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.


At low loads efficiency isn't so high of course, but you can't call it bad either since even with 40W of load it is only a hair away from 70% and with 100W load it easily surpasses the 80% mark. Nevertheless the general rule applies in this case too, the higher the capacity of the unit the lower the efficiency at loads under 10% of max rated capacity. So if your system idles at low power and doesn't need lots of juice even at full load, then you better buy a smaller capacity unit and not a 1200W beast which would be overkill.

Let's check the iPower Meter's readings.


About the same story as with the normal loads. Only this time voltage readings are not so off but this is mainly due to the small load variation (40-100W). Efficiency is even less accurate and power readings are also off track. Finally once more the current readings on the minor rails are extremely accurate but this does not apply to current of the +12V rail.

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.


Efficiency on the 5VSB rail is nothing to write home about. At the first two tests it's below the corresponding threshold and only at the last two, it pass the 70% mark. The good thing is that with full load, 4A, it manages to achieve a decent efficiency level of nearly 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 is low enough at 0.57W and meets the ErP Lot 6 2010 requirements, so we are left quite satisfied here.