Verdict: The most power-efficient PSU we've seen.
Rather confusingly, Be Quiet! uses the same Dark Power Pro name for nearly all its PSUs, bar the bargain-basement Straight Power series. To make sure you're buying the latest Dark Power Pro, check that the middle two digits of the SKU number read 'P7'.
This Dark Power Pro splits its 650W across four 12V rails, each rated at 20A. Four rails is quite unusual for a 650W PSU, and means that each of the power-hungry components in your PC has its own rail, so they shouldn't interfere with each other. The 12V1 rail powers the motherboard; 12V2 powers the 4-, 6- or 8-pin CPU cables (use only one); 12V3 the eight Molex, eight S-ATA and single FDD plugs; and 12V4 the two 6+2-pin PCI-E connections. The inner workings are kept cool by an extremely quiet 120mm fan, which usefully continues to spin for several minutes after the PSU switches off. This Dark Power Pro also takes modular cables to a whole new level. All the cables, bar the constantly used 20+4-pin ATX, are modular - even the CPU cables. Providing that your PSU bay can take a 180mm-long unit, you can build an incredibly neat and tidy - and therefore potentially cooler - PC with this PSU.
At half-load, the Dark Power Pro proved to be an incredible 87 per cent efficient. It managed the same efficiency at full load, drawing just 744W from the mains to generate its full 650W. The output from all the rails stayed well within the tolerances stipulated by the ATX spec, even after running at full load for a couple of hours.
Conclusion
The Dark Power Pro is quiet and incredibly power-efficient. Be Quiet! has also gone to great lengths to ensure that the amount of cabling required is kept to a bare minimum. As the Dark Power Pro is as modular as we'd ever want a PSU to be and can output its full 650W for hours, it deserves its place in your mid-range PC.
