Final Thoughts and Conclusions
No fan – no moving parts – no noise!  Like its big brothers, the new X Series 400W fanless PSU incorporates several significant advances in PC power supply design that result in excellent performance, high efficiency and the ability to operate without a fan.  Moving the +3.3V and +5V VRMs to the modular DC connector board was a very smart move.  Add to that all modular cables, excellent voltage regulation, clean outputs and a 5-year warranty and you have a very nice power supply. 

The MSRP for the Seasonic X Series 400W Fanless power supply is $139.99 USD and the unit is scheduled to become available in August 2010.  If you want a true fanless power supply then the X-400 is the answer.  Keep in mind that for an additional $30 you can buy a Seasonic X Series 650W PSU, which is also capable of running in silent mode (fan turned off) at the lower power levels but will supply an extra 250W of fan-cooled power if you need it.

Seasonic X Series 400W Fanless Power Supply Review - Cases and Cooling 40

•    Silent operation (0 dB)
•    400W continuous DC output
•    Excellent efficiency across a broad range of loads
•    Excellent voltage regulation
•    Low AC ripple even at 100% load
•    Single +12V output can deliver up to 33A/396W
•    One PCI-E connector (6/8-pin)
•    Active PFC with universal AC input
•    Sleeved cables with gold-plated connectors
•    Green Innovations (long life cycle, high quality components, high efficiency, and value)
•    5-Year warranty

•    Slight jump in AC ripple on +5VSB rail at moderate load

Seasonic X Series 400W Fanless Power Supply Review - Cases and Cooling 41
Seasonic X Series 400W Fanless PSU

I would like to thank our friends at Seasonic for sending us the X Series 400W fanless PSU to review.  Be sure to use our price checking engine to find the best price on any of Seasonic’s great products or anything else you may want to buy!
And if you have any questions or comments about the article, or would like to see what others have to say about the Seasonic X Series PSUs, just click into our Case, Cooling and Power Supply forum to join in the discussion!

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