Verdict: Quiet, stable and efficient
Before this issue, we'd only seen one Be Quiet! PSU - the inefficient and backwards-looking Dark Power Pro 600W. Fortunately, Be Quiet! went back to the drawing board when it came to designing its latest mid-range PSU, the Straight Power 550W.
Despite its comparatively low 550W rating, it has four 12V rails, a feature usually only seen on much more powerful PSUs. This is a definite plus, since it means that power-hungry components won't have to share a rail. In the Straight Power 550W, 12V1 powers CPU1, 12V2 CPU2 and the second PCI-E plug, 12V3 the motherboard and disk drives, while 12V4 powers the primary PCI-E plug. Each of these rails is rated at 18A, with a maximum combined output of 41A (492W). Also present is a 32A 3.3V rail, a 30A 5V rail, a 0.5A -12V rail and a 3A 5VSB rail.
In our tests, the Straight Power 550W performed admirably, with all the rails providing a stable voltage even after running at 100 per cent load for an hour. It was also efficient, averaging 81 per cent at full load, and drawing 676W from the mains to produce 550W. No doubt, this is partly down to the quiet 120mm fan that helps to keep the inner workings of the Straight Power 550W cool. At the time of writing, the Straight Power 550W hadn't received CrossFire certification, and was only certified for running two GeForce 7800 GTXs or lower in SLI.
Conclusion
While the Straight Power 550W is 100 per cent stable, efficient and has braided cables, it's fairly expensive for a 550W PSU, retailing for the same price as the Antec Neo HE 500, which has modular cables. The Straight Power 550W may cost around £10 more than we'd like, but it's still an excellent PSU and well worth shortlisting.
