When the PSU was working with an APC SmartUPS SC 620, the UPS would report overload at a load of over 340W from the mains as well as batteries. I had no problems with using the power supply jointly with that UPS.

At a load of 438W the voltage ripple amounts to 23 millivolts on the +5V rail, to 25 millivolts on the +12V rail, and to 15 millivolts on the +3.3V rail. There’s only high-frequency pulsation here.

The cross-load diagram may not look as perfect as those of PSUs with independent voltage regulation, yet it is good anyway. The +5V is somewhat unstable, but it is going to fit into the “green zone” in a modern computer where there’s usually a load of 50W at maximum on this power rail.

FSP install fans from Protechnic Electric into its power supplies whereas the Zalman features a high-quality and low-speed Minebea-Matsushita 4710KL-04W-B20 fan.

The fan speed is regulated linearly from 634 to 1350rpm. Although there is no flat stretch in the graph in the area of small loads, the PSU is very quiet. The fan only reaches 800rpm at a load of 150W. Comparing the Zalman ZM460B-APS and the Seasonic S-12 SS-500HT, the latter is somewhat quieter at full load, but the difference is barely perceivable, especially considering the other noises in a computer that consumes so much power. So, both these PSUs are very quiet, almost silent.

Contrary to my expectations, the efficiency of this PSU is good, although not record-breaking, reaching 83% at the maximum. It is 80% at full load. The ZM460-APS had similar results, though.

So, there is in fact no big difference between the ZM460-APS and the ZM460B-APS. The second model has a slightly higher load capacity of the +12V rail, has a second graphics card connector and two more SATA power connectors. One of its heatsinks is larger, but this doesn’t affect the speed of the fan, which is the same as with the previous model. The PSU has good parameters and stands out among its competitors with its very quiet operation. The Seasonic S-12 is the only other model that can challenge it in this respect, so the ZM460B-APS will be a good choice if you need a quiet power supply. If you’ve already bought a ZM460-APS, you should not regret your having not the latest model because the B version is just a minor improvement upon an already superb power supply.