Testing and conclusion
400w+ PSUs should be able to cope with any stock system. The real test presents itself when we crank up the Vcore and CPU speed. We can infer that the lower the voltage fluctuation on given voltage lines, the better chance the CPU has of being stable at that speed. Firstly 12v.
The Zalman ZM400A-APF is a pretty consistent performer with just over 0.2v fluctuation in 4 hours of relatively heavy load. The 12v line is reasonably close to what we expect. The Samcheer, though, is that little bit better. The CPU is driven off this line, so it's important that we receive a consistent, ripple-free power source.
The 5v line drives, amongst others, the optical drives, system RAM, motherboard and USB devices. The Zalman does well here too.
The Zalman could provide the most accurate voltage lines in the world and it could be the best-looking PSU on the market, but if it can't deliver performance without relative silence, it's failing its main objective. The sound levels are entirely subjective. The Zalman succeeds in its primary objective, it seems.
Conclusion
Priced at around £80, the Zalman ZM400A isn't cheap. However, it does deliver a consistent power source at high load levels, and it does this without sounding like a turbine. The all-range voltage selection is a thoughtful feature. Depending upon your outlook, a second floppy connector and longer cable length would have been preferable. You could also argue that the redundant floppy connector and lack of cable length is better. It all depends upon your individual circumstances. £80 is steep for a 400w PSU. Whether it's worth it or not depends upon how much you value silence. Recommended to those looking for uber-quiet rigs.
An excellent product that's just a little too expensive to be recommended without reservation.
