be quiet! System Power U9 500W PSU Review: Affordable and Quiet

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Bottom Line

Every time I have to evaluate a budget power supply I can't help but worry that it won't survive our tests. If a unit fails, I have to wait for the company to send a second sample and the failure can damage our test equipment. Thankfully everything rolled smoothly with the SU9-500 since it uses a reliable platform provided by Channel Well Technology (CWT). This might be an older design, but it has been upgraded with the addition of a couple of DC-DC converters, which handle the minor rails. Those converters offer good performance in tough scenarios where the load at +12V is the minimum while at 5V is high, and vice versa.

The SU9-500 faces strong competition from the EVGA 450 BT, which can have an explosive character under tough conditions, and the Corsair CX450. However it stacks up pretty well, offering similar performance levels and much quieter operation. I was highly impressed by the low noise of this unit, even under high operating temperatures.

The unit also uses good components, including Elite caps, considering its price tag. The only changes that I would like to see are the bulk cap, which ideally should be rated at 105°C and a rifle bearing fan used instead of a sleeve bearing one. Those two changes would affect this unit's price but not significantly, while at the same time, would highly increase its reliability. 

Although personally I would avoid using a lower than 80 PLUS Gold or ETA-A efficiency power supply, there's a huge crowd out there for budget power supplies. For those consumers the be quiet! System Power line, including of course the SU9-500, is a very good choice, especially for the building of a silent office PC. Just be prepared to live without modular cables.

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Disclaimer: Aris Mpitziopoulos is Tom's Hardware's PSU reviewer. He is also the Chief Testing Engineer of Cybenetics, and developed the Cybenetics certification methodologies apart from his role on Tom's Hardware. Neither Tom's Hardware nor its parent company, Future PLC, are financially involved with Cybenetics. Aris does not perform the actual certifications for Cybenetics.

Contributing Editor

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.