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Efficiency, According to the 80 PLUS Specification
Efficiency Across the Power Spectrum
In the test lab, the 480 W power supply follows and then surpasses the performance of the 580 W model. It conforms to the 80 PLUS spec even more closely, sporting particularly high efficiency at low loads. At 25 W, for example, the 480 W PSU comes close to 80% efficiency, which is a respectable number that ranks among the best performances we've seen. In standby, it only draws 0.18 W.
Our lab tests show that be quiet!'s E9 CM 480 W doesn't encounter any regulation issues, and also achieving low low ripple and noise values on the DC rails.
Last but not least, even when you're in a quiet room the Straight Power E9's fan can only really be heard close to the power supply itself.
A Peek at the PCB
The 480 W PSU's interior looks a lot like the 580 W model we've already reviewed. All be quiet! power supplies are manufactured by FSP and are similar to that company's Aurum family. Taiwanese firm CapXon makes the Straight Power E9's capacitors. Although they're not the premium caps from Japan, which FSP uses in its own-branded power supplies, they're still decent and shouldn't cause problems.
We did notice an extra ceramic capacitor in the mains-side circuit. Its task is to eliminate the chirping sound that sometimes emanates from power supplies. Another design feature intended to help reduce noise is a fan mount sitting on rubber grommets. This prevents vibrations from being amplified by the power supply enclosure. The manufacturing and soldering quality are both impeccable. Our only complaint is that FSP does not use heat shrink tubes to cover the locations where cables are soldered onto the PCB.
The be quiet! Straight Power E9 CM 480 W is very quiet and boasts an 80 PLUS Gold rating. It demonstrates no apparent weakness in our testing, and offers high efficiency across the entire load spectrum. Its feature set and quality are top notch, and although it is actively cooled, this power supply is the next best thing to fanless. Unfortunately, it isn't available to our U.S. audience, and only stands in as a comparison point for our other two passively-cooled contenders.