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The fan inside the unit is a San Ace 120 – Model 9S1212F404. This is a 120mm unit (140mm fan in the AX1200) and it is a 7 blade design rated at 12v/0.19A. This fan normally spins in the 1200rpm zone, but has a maximum rating of 2,400 rpm creating 40dBa – we will look at this later. If you are interested in the full range of Sanyo Denki fans then check out this page.
Corsair are keen to extoll the virtues of their Hybrid Silent fan control system – it offers 3 modes of cooling which is dependant on the current status of power load. up to 20% load for instance the fan is disabled which generates no noise and then between 20% and 50% load it spins into low fan mode. Above this it then turns into performance mode for demanding load requirements.
Sanyo Denki are well known to make some of the best fans in the business, but they are noticeably more expensive than many others. It is good to see Corsair not cutting a corner here with a cheap fan.
Internally, the design is neat, and while there is obviously less physical space when directly compared with the AX1200, there are no glaring build issues. Wiring is noticeably tight, ensuring the best possible connection quality. Soldering quality is high as we would expect.
The Corsair AC850 is using a design which means that the 3.3V and 5V DC outputs are situated on an independent DC output connector board.
The connector board features an integrated voltage regulation module (VRM) which produces the 3.3V and 5V output directly from a low current 12V DC input. This is a similar principle to the AX1200 we reviewed and it results in a much higher efficiency rating compared to traditional designs that place all the DC output connectors on the same board.
The capacitors used for the PFC stage are 390uF rated to 105C. This Corsair unit boosts efficiency by minimising the loss in the PFC stage by switching the primary power on and off when the cycle is at 0 voltage and 0 current.
The Corsair AX850 uses a high quality double sided PCB design which offers advantages when compared against standard PCB layouts. The primary point to note is that this specific design doubles the amount of copper used for traces and return planes and it also increases the efficiency as a result of lower resistive losses which helps to improve cooling characteristics. The AX850 also incorporates ‘through-hole' soldering which means higher levels of reliability.
As we would expect there is over current and under voltage protection and the PSU conforms to all required international safety standards. Over current protection (OCP) for example is present on all rails, including the single +12V rail (which can deliver 70 Amps – 840w). Over Temperature Protection (OTP) and Short Circuit Protection (SCP) are also included.
All of this is covered by a full 7 year warranty for added peace of mind.
