I must also say that the PSU uses standard thermo-sensors, standard fans and standard connectors, so it can be attached not only to its own panel, but also to fan & temperature control panels from other manufacturers. There is another collection of cables included with the PSU for that purpose so that you could connect both the sensors and both the fans at once. It’s nice to see such care about the user when many other manufacturers deliberately make their designs incompatible with others’ (using non-standard connectors, for instance) for the user to buy accessories from that manufacturer only.
The unit yields rather stable voltages, especially considering the allowable load range for the +5V and +3.3V rails, but I wish the +5V were lower in the bottom right of the diagram since it is there that most modern computers belong in.
At a load of 540W the voltage ripple was 20, 23 and 28 millivolts on the +5V, +12V and +3.3V rail, respectively.
The fans installed in the PSU are labeled as “Sunbeamtech”, so I can’t tell you the name of their actual manufacturer. Both fans are black, with shiny blades and without any highlighting. The number of blades is somewhat unusual: the smaller fan has 11 and the bigger has 9.
As promised by the manufacturer, the 120mm fan is really very quiet. Its speed isn’t higher than 1500rpm even at full load (the speed was managed automatically during the tests). It’s worse with the 80mm fan which can spin up to 3000rpm and become rather noisy. The control panel allows you to find an optimal balance of the speeds of the two fans, though.
The efficiency of this PSU isn’t high, barely notching 80%. The power factor is quite typical for a unit with active power factor correction.
So, Sunbeamtech has made a successful enough debut in our reviews. The SUNNU550 features good electrical characteristics and excellent functionality too. It has detachable cables (and unlike the cable-free Ryanpower2, the SUNNU550 is up to the latest requirements), allows to control the speed of the PSU fans and even connect an external fan, and has two temperature sensors accessible from the outside. What’s important, the additional features do not look like useless trumpery, but are really well thought out from a technical standpoint. So, that’s indeed as fine a debut as you may wish.