Amacrox Calmer 560: Silence is Golden

Conclusion

The Amacrox Calmer 560 targets a specific group of users. The 400W output is enough for most midrange and lower systems, but potential buyers should be aware that it only includes a 4-pin ATX12V connector for the CPU and not the 8-pin some boards desire, and there's only a single 6-pin PEG connector. That's enough to support midrange to high-end graphics cards with current GPUs. Given that this is a fanless PSU, we expect most users will be going for a lower end fanless GPU as well, so the lack of multiple PEG connections shouldn't cause any difficulties. In short, this power supply is a great fit for HTPCs, quiet office systems, or PCs that happen to be located in bedrooms.

The cable harnesses are very short, which again limits the versatility of this unit. It will definitely not work in a full-size tower, since the cables are not long enough to reach the different motherboard jacks, let alone the HDDs and DVDs. However, the Calmer 560 is a standard ATX size, so it can mount in smaller midsize and mATX cases without difficulty. For an HTPC or small mATX setup, of course, the shorter cables should be a perfect match. Just make sure the case can handle a heavy PSU, as this unit weighs around 4kg/8 lbs.

The performance is average at best, with quite a bit of voltage drop at higher loads. Most of the rails - including the important 12V rails - stay within specs even with 10% overload, so it should be adequate. The efficiency is very good and stays above 80% at most loads and input voltages. With a maximum of 86% using 230VAC, the Calmer 560 won't waste a lot of power, but optimal efficiency requires a load of ~100W or more. The high efficiency is important considering the fanless design; you definitely don't want to have to deal with any extra heat.

Amacrox PSUs are not yet available in the US, but the company is working to change the situation. In Europe, Amacrox is already a recognized brand that's available at most online stores. The price of around 150 EUR is quite steep considering the specifications; many competing power supplies offer virtually silent operation using a low RPM fan for half the cost of the Calmer 560. In the US this price would be more than $230, which is definitely too much for this product.

The price is too high for us to recommend this power supply, and fanless can be a bit of a concern in actual practice. Sure, a fanless PSU might be fine, provided you have at least one decent case fan; or maybe a fanless GPU with other low-RPM case fans. Removing all the fans in a modern PC, though? You'll want to be very careful if you try that approach. Still, we know there are people out there who want nothing other than pure silence, and that is what they get with the Amacrox Calmer 560. We recommend staying at loads closer to 200W rather than pushing for the 400W rating of this PSU, but then it's quite difficult to get silence on a 400W system anyway.