Be Quiet! Straight Power E9 680W Review

Our cross loading procedure is designed to rigorously test the stability of the main two rail combinations. We push the maximum rated current and wattage through the 12 volt rail(s), and then through the 3.3 and 5 volt rails combined, and see if the power supply is capable of delivering its specification for those. However, meeting the specification is not enough, the power supply must also maintain strong voltage regulation and noise/ripple to have “passed the cross load test. 

The cross load test is a “worst case scenario” for the two main power delivery rail mechanisms (12v and 3.3+5v) and so the power supply will always deliver slightly lower than realistic/expected results. However, this is not necessarily a realistic test and it is just a case of pushing a power supply’s rails right to their rated limits to see how well they can hold up.

12 Volt Cross Loading

Voltage regulation was a bit worrying on the -12 volt rail while the others held up reasonable well given the unrealistic battering we put the 12 volt rail under. The -12 volt though isn’t really use much by your PC at all so it is nothing to be worried about.

Ripple and noise was also strong given the magnitude of the 12 volt load and was less than 25mv.

5 and 3.3 Volt Cross Loading

Voltage regulation at 5 and 3.3 volt cross load was less than 4.5% which is pretty good, the only exception was again the -12 volt rail which is something Be Quiet definitely need to work on.

Noise and ripple on  the 3.3 volt rail was very strong though the 5 volt rail achieved 33 mv which is well over half way towards reaching ATX specifications of 50 mv.