The Riotoro Onyx Power Supply Review: 650W & 750W Tested

Hot Test Results

Great Wall’s platform overall delivers a good power quality. As a matter of fact, the platform’s overall performance seems to have improved significantly since the last time we reviewed a similar unit, indicating that the OEM is candidly trying to improve.

We can see that the voltage regulation is significantly improved and very good for PSUs of this class and power range, at 1.2% on the 12V line and lower than 1.5% on the minor lines. The power quality readings are not going to break any performance records, but a maximum voltage ripple of 52 mV and 54 mV on the 12V line of the 650W and 750W models respectively is good, less than half that of the recommended design limit. Both units appear to be a little stressed when heavily cross loaded, with abnormally high ripple appearing on the 12V line, but the reading still do not go anywhere near the 120 mV design limit.

High ambient temperatures have a significant (but not abnormal) impact on the energy conversion efficiency of the Onyx 650W and Onyx 750W PSUs. The average nominal load range (20%-100%) efficiency drops by 0.7% for both units, with the drop almost evenly distributed across the load range, hinting that there are no component quality or stress issues. The nominal load range (20%-100%) efficiency is now 87.3% and, theoretically, both units sustain their 80Plus Bronze efficiency rating even under these operating conditions (the efficiency certifications are being performed with an ambient temperature of 25°C).

A quick glance on the sound pressure level charts shows that the noise levels of the Onyx units are unusually low for units with just an 80Plus Bronze rating. Both units are certainly going to be audible with a load greater than just 200 Watts under these operating conditions, but the noise levels of the fans only slightly surpass 46 dB(A) under maximum load, a relatively low reading taking into account the unit’s power output, efficiency and heatsinks. The reason for this is that the used fan is most likely slightly undersized for the cooling needs of these units, as the internal temperatures do reach uncomfortably high readings when the Onyx PSUs are heavily loaded under these working conditions.