The PSUs worked together with an APC SmartUPS SC 620 at loads up to 372W (from the mains) and 340W (from the batteries). At higher loads the UPS would report overload after switching to the batteries but continued to operate.
Alas, the output voltage ripple is near the permissible maximums on all the power rails, and short-terms spikes even exceed them.
The cross-load characteristics aren’t good, either. The +5V and +12V voltages sag heavily under load. That’s not a critical, yet unpleasant, situation.
The PSU is cooled by an 80x80x25mm ADDA AD0812UB-A70GL fan, the same as in the above-discussed Antec TruePower Quattro TPQ-1000.
But unlike with the Antec PSU, there is a linear dependence between the speed and load, without a flat stretch at low loads. Moreover, the fan is as fast as 3600rpm at full load. So, there is no silence here but the temperature of the output air is much lower than with the Antec. This PSU won’t die from overheat.
The efficiency is high at about 85% through most of the load range. It goes down somewhat at the end of the graph, yet still remains higher than 80%.
The result of the last test cannot change the overall impression, though. The Silver Power GuardianX SP-1000E is not an interesting product if compared with the available alternatives. It is noisy, its voltages are not very stable, and its output voltage ripple violates the permissible limits.