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Corsair AX850 Power Supply Review

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.

Image courtesy of Corsair

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.

image courtesy of Corsair

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.

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  1. These Corsair PSUs really are leading the way. Nice temperature results too. I used to read reviews with PSUs outputting over 50c.

  2. that is great. the pricing is good too £90 less than the 1200W.

  3. Corsair really do deliver such great products. this is an ideal next purchase for a buddy of mine who is building a high spec gaming rig with a GTX480 in it.

  4. Excellent review, seems to be a killer product all round. Price isnt bad considering. I know PCpower used to charge 300 quid for their 1200W and over 200 for a 850/900w

  5. Man this site is active, every day one or two reviews on it !

  6. The fan in that seems pretty much the best you could use. great job by Corsair and they deserve to be getting a good rep in this market. Box art is brilliant.!

  7. Well this is sweet. bit more than I like to pay, I got an enermax last year for 100, still working great 🙂

  8. Im really glad this unit came out. the AX1200 was a great showcase of technical ability, but it was so expensive, I think only people who have dual GTX480s would buy it.

    This seems much more valid for todays market, and while its 150, its ‘affordable’, If you think about it, this should last 3 years easy even with new hardware, so its a long term investment. I wish a video card I would buy now for 150 would still be a good option in 3 years..

  9. Yeah, always stuns me when people build a great gaming system then buy a no name 800w brand for 35 quid in their local store. Then bitch when the system crashes every 5 minutes.

  10. This is my next PSU, without question. should last me to 2014 🙂

  11. Gimmie some sugar

    Brilliant review. cross loading results are superb.

  12. Been waiting on this one for a bit now 🙂 hasnt disappointed.

  13. I need a new PSU, but do you think they will release one at £80 🙂 ?

  14. Excellent, most excellent. Now I just need to rob a bank.

  15. These designs are so efficient and its really setting them apart. Enermax should have an answer soon however.

  16. Corsair are having such a great year. them and MSI seem top of the field.

  17. 150 is out of my price point. normally. I might try and make an exception this time, funds permitting. I need something I can rely on to last me for years also

  18. Another kick ass product from the Corsair group. They really are pumping them out lately. efficiency is great.

  19. over 90 percent efficiency is impressive shit. Would save quite a bit of money with this over the year, Once I convince my wife that is why I need it however,

  20. Another top review KG. I think this is going to sell very well for corsair. I hope they bring out a 650W model and can get it under £100

  21. Seems this range is breaking all records in the PSU industry. How many more models are they going to make, or is it just two ?

  22. Excellent product from a company who seem to be really putting a lot of resources into delivering the best possible units to market.

  23. Very impressive testing results. much better value than the 1200 unit in the same family

  24. The hybrid fan feature is great as it should mean the psu fan stays silent when you’re not gaming or folding or something like that. More psus should do this!