Output Voltage Stability
We checked out the stability of the output voltages depending on the load in two steps. You see, the three reviewed models from ASUS differ from the standard 300W PSU in their higher acceptable current on the +12v rail, up to 18A. It is done because modern computers consume more power from this rail. For example, new models from Zalman indexed “B” (the ZM300B and the ZM400B) also claim to provide a maximum current of up to 18A on the +12v rail (see our 3 Zalman Power Supply Units Roundup for details). Meanwhile, a majority of older 300W PSUs have 15A at most on this rail, as the ATX standard dictates. So, in order to compare the results of the units from ASUS with previously-tested models we performed the first set of our tests using a maximum current load of 15A, and then, to estimate the PSUs’ stability under the maximum load, we performed a second session with a load of about 18A. The tables below show the averaged results of all the three units; the diagrams contain the results of the A-30H.
You may note that the PSUs perform well under the “standard” load as well as under the increased load. The voltage range on the +3.3v rail might be smaller, but this rail doesn’t have its former significance in modern computer systems anymore: many low-powered devices are equipped with their own regulators (for example, the CPU and the GPU). Moreover, notwithstanding our somewhat artificial trying to put a higher load on the units (the real computer is unlikely to meet the swings and misbalances of the load as on our testbed, and thus will have a smaller voltage dispersal ranges), none of the output voltages of the PSU exceeded the standard-regulated limits (±5% of the nominal value).
Lastly, I’d like to say that the units come with six connectors for IDE devices, with two power connectors for SATA devices, and AUX and ATX12V connectors. The AUX cable has the 16 AWG section and the other cables have the 18 AWG section, save for the FDD cables that are undemanding on the maximum currents.
The units come in a simple white box with four 1” screws for fastening them to the system case.