Antec Phantom 350W Fanless PSU Review
 

Most of the above listed features are standard with the majority of quality power supplies, but the 85% efficiency is by far the highest rated value of any currently available PSU. Much like the fanless design, this is big news. Mechanically, efficiency is the ratio of useful energy delivered by a machine to the energy supplied for its operation. In power supplies, the rest is given off as heat. The industry standard is currently close to 70% with quality units ranging between 75%-80%. 70% vs. 85% may not seem like much, but consider this mathematically ideal situation: using a 300 watt load (more than adequate even for high-end systems), an 85% efficient PSU will give off 45 watts as heat; a 70% efficient PSU will give off 90 watts as heat - that's twice as much! So, even 15% of extra efficiency translates into half the heat output.

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