The oscillograms fully repeat the results of ZM400A-APF, while the voltage stability parameters are somewhat different:
The stability of the +5V voltage degenerated more than the others, by about 2%. This is mostly because of the higher maximum load current on the +12V power bus – of course, it was higher in our tests, too. The stability of the other voltages changed slightly, so this unit also gets our applause.
The first visual inspection made it clear that ZM400B-APS was just a slightly improved ZM400A-APF. It boasts the same highest quality of manufacture and a very quiet fan. Considering the small difference in price, the newer model has a higher appeal to the customer.
So we have tested three power supply units selling under the Zalman brand. According to the company’s website, the model range now includes four models: the three we have just introduced to you plus ZM300B-APS model.
All three units are manufactured for Zalman by FSP Group, a respected maker of high-quality PSUs. The quality is high in this case, too, and the attention to every minute detail is really impressive. The characteristics of the devices also match best models from other renowned companies. By the way, I think the argument about the best PSU, whether it should come from Zalman or from FSP, doesn’t make any sense, since Zalman actually sells top models from FSP.
300W ZM300A-APS can be regarded as an excellent choice for mainstream computers: 300 Watts is enough for a majority of system configurations, save for the most advanced ones. You shouldn’t be misled by the company’s claims about its noiselessness, though. This PSU uses a good, but quite ordinary 80mm fan for cooling.
400W ZM400A-APF and ZM400B-APS are an ideal choice for hi-end computer systems, including two-processor workstations that put strictest demands on the power source. If you have a choice between these two units, you’d better go for the newer model, ZM400B-APS, which surpasses 300W PSUs in all parameters, while the ZM400A-APF won’t always help you if the standard 300W PSU is insufficient for your system. Both models are equipped with very quiet fans from NMB with an effective temperature control circuit. This feature distinguishes these products from other PSUs of the same wattage.