Verdict: 850W of stable power, but it's pretty noisy
At the moment, there seems to be two schools of thought on how to design a high-wattage PSU - either squeeze it into a standard-sized enclosure, so that it will fit in any ATX case, or use a larger one that will only fit in bigger ATX and WTX cases. The problem with the former approach is that inside a smaller case, all the PSU's components will have to be densely packed together, so a powerful (read noisy) fan will be required.
Be Quiet! appears to have adopted this approach when designing the Dark Power Pro 850W and, as a result, its 120mm fan buzzes rather annoyingly, especially at full speed. Inside the diminutive case are four 20A 12V rails with a maximum combined output of 58A (696W). 12V1 powers the motherboard, 12V2 the 4-pin ATX12V CPU connector, 12V3 the 8-pin EPS12V CPU connector, second and third PCI-E plugs and three of the modular sockets. 12V4 powers the first and fourth PCI-E plugs plus the other three modular sockets. All four of the PCI-E plugs are modular, but two of these are the new 6 + 2-pin type designed to support the forthcoming 8-pin PCI-E sockets that will debut on ATi's R600 series of graphics cards.
The Dark Power Pro 850W hasn't yet received SLI or CrossFire certification but, given its 100 per cent stable output and four PCI-E connectors, it should easily support a pair of 8800 GTX or two X1950XTX cards.
The Dark Power Pro 850W is also reasonably efficient, hovering between 79 and 80 per cent depending on the load; when producing 850W, it drew 1,075W from the mains.
Conclusion
The Dark Power Pro 850W is pricey for an 850W modular PSU, although its support for 8-pin PCI-E graphics cards should give it longevity.
However, if you stretched your budget by a further £5 you could buy the 8-pin PCI-E upgraded EGA850DXX version of the much quieter, more efficient Enermax Galaxy EGA850EWL, although it will only fit in larger cases.
