Conclusion

On the whole, I can’t say anything bad about either of the tested power supplies. Products from FSP Group and Topower feature a highest quality of manufacture, and the particular models I have reviewed here easily meet their specifications.

The FPS Zen was obviously designed as a fanless power supply from the start, while the TOP-420NF model from Topower is a redesign of an ordinary actively cooled PSU. As a result, the Zen can really be regarded as an absolutely silent PSU whereas the TOP-420NF is quiet, but not completely silent.

Moreover, the FSP Zen is better of the two in other parameters: modern computers don’t need a high load capacity of the +5V rail, while the load capacity of the +12V rail in the Zen is theoretically no worse than in the TOP-420NF and is even better in practice due to a smaller voltage ripple and a higher stability of the output voltages. Thus, the FSP Zen seems to be a better choice as a power supply for a noiseless computer.