It is very strange indeed to test a product by a company that is called be quiet! only to find it rather noisy. Power Zone apparently not only breaks with the semi-modular tradition as this unit also isn't as quiet as other be quiet!'s offerings. Important because Germans are known to be extremely sensitive to noisy products, the Power Zone 850 W unit must then be for those markets be quiet! isn't inherently native to. Putting aside its for be quiet!'s standards increased noise output, the Power Zone 850 W did well in all other areas, achieving tight voltage regulation at +12V, very good ripple suppression on all rails, and an overall efficiency level that not only puts Bronze, but many Silver units to shame. Its build quality is very high and in part justifies its high price, while the cooling fan uses Fluid Dynamic Bearings, which are considered the best and come with a very long lifespan. The fact that the PSU can directly power and control three case fans will also save you some money as you would otherwise probably have to buy additional fan controllers. The main downside of this unit is, in my opinion, that it isn't Gold certified since it could easily meet the 80 Plus Gold specifications with, at most, a few very minor modifications. Most users would consider its price tag on par with the competition if it were officially Gold certified, but as it currently stands, its price obviously looks very high for a mere Bronze PSU. So be quiet! is left with two options: Either release an upgraded Gold-certified version or lower the price closer to that of other Bronze units. I know for a fact that its efficiency is much closer to Gold than Bronze, but many users don't and never will be privy to that knowledge. Also, like with the Power Zone 1000 W, ripple shot through the roof for a very short period of time only during the "PSU OFF TO FULL 12V" test. While a highly unrealistic scenario, most PSUs I have evaluated still managed to pass this specific test without a hiss, so I expect the same from this PSU.

To sum up, the first priority of be quiet! should be to find a way to increase availability of this unit in the States while lowering its price to that of a Bronze unit, although the efficiency I measured easily met Silver standards; efficiency was even close to that of a Gold-certified unit. You shouldn't expect much in terms of noise as the unit is definitely not a pure be quiet! product in that regard while operating at high loads and under tough conditions. So you had better look at another PSU in their portfolio if you want a truly silent PSU.