Together with an APC SmartUPS SC 620 this PSU worked at loads up to 300W (from both the mains and the batteries) and the switching to the batteries was performed without problems. Well, it is only PSUs with active PFC that may have potential problems with UPSes – the Superb 550 doesn’t belong to that class. The PSU also passed the full load test normally.
The output voltage ripple at full load is far within the permissible limits.
As the load on the +5V and +3.3V rails grows up, the respective voltages sag and violate the permissible 5% deflection. But considering that these rails are not loaded heavily in modern PCs, the only real drawback I can see is that the +12V voltage sags at loads of over 250W. Well, even a gaming system with a Core 2 Duo processor and one graphics card like GeForce 8800 GT consumes less – so you should have no problems with this PSU.
The fan works at a constant speed of 850rpm until a load of 170W and accelerates steadily hereafter. As a result, the PSU is very quiet at low loads and average at loads over 200W. Interestingly, the above-discussed PSUs, also manufactured by AcBel and with similar fans, proved to be quieter in practice.
The efficiency barely reached 80%, which is a very modest result for a modern PSU. The power factor is no higher than 0.65.
Gigabyte’s new PSU is a good entry-level product. It doesn’t boast exceptional specs or functionality, but shows no problems within the scope of its intended applications. Featuring good quality of manufacture, quiet operation and low loads, sufficient wattage (even for gaming systems), this PSU should be a good choice for both office and home PCs if you find its price reasonable.