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 Venom Power 550W 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 Venom Power 550W. 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.


Since Akasa doesn't mention anything about the max operating temperature that this unit can stand, we tried to stay well below 50°C since we managed to blow our first sample during the full load test with an ambient near that temperature. As you can see voltage regulation at +12V and 3.3V is nothing to write home about but at 5V it's outstanding, for our standards and equipment. Of course we would highly prefer a looser voltage regulation at 5V if this would provide much tighter results at +12V, which is far more important. Also we noticed that +12V actually starts at way higher voltage than the nominal, apparently to compensate the large voltage drop at higher loads. Nevertheless a large deviation is still the same whether the initial voltage starts high or low. Also all rails should keep their voltages close to the nominal ones, no matter the load they handle.
Leaving voltage regulation aside, let's check efficiency now. This is constantly above 80% at all normal load tests and peaks at 84.5% with 40% of max rated capacity load. Not ground breaking efficiency, that's for sure, but at least decent for its category. And now it is time to deal with the real bad stuff and this is of course performance with highly unbalanced loads among rails (or CL tests). Performance here is bad and typical of an older group regulated design. Also the high voltage drop of the +12V rail at CL2 test clearly proves that the small Venom cannot handle over 500W of power on this rail while the minor rails are lightly loaded. Too bad that Akasa claims that the same rail can deliver up to 540W of power alone. Finally up to the 40% load test the PSU's fan was almost inaudible and only at higher loads/ambient the controller increased its speed leading to higher noise output, without however being annoying at any time.

Efficiency at Low Loads

In the next tests, we measure the efficiency of Venom Power 550W 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.


Efficiency with 40W load is very low. With only 20W more load it drastically improves and with 100W it manages to pass the 80% mark. From a PSU that doesn't feature even the plain 80 Plus badge, efficiency above 60W load is decent.

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 registered a very loose voltage regulation which exceeded the 5% limit by far, so we think that Akasa should change the power specifications of this unit and declare a lower power output for this rail. Regarding efficiency on this rail, at the first two tests it's high enough while on the last two it's close to the corresponding limit that the ATX spec sets.

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).


Phantom power is very low, lower even than the threshold that the future ErP Lot 6 2013 sets (0.5W). This is something very good of course since it means lower power consumption, something beneficiary to the environment. You cannot imagine how much energy is wasted by products, not apparently desktop PSUs, that still are not ErP Lot 6 compliant. Thankfully over the last years more and more manufacturers try to comply with this directive.