The AX850 proved to be a solid performer. Although its voltage regulation was not jaw dropping, +12V and 5V rails stayed under 3% and only 3.3V reached 4% deviation. The high efficiency levels even under very high ambient temperatures, the excellent ripple suppression and especially the great performance of all rails in the Advanced Transient Response tests showed the high class of this PSU. You see we don't encounter very often PSUs that manage to pass all of the afore-mentioned tests. Finally the fully modular design and the very quiet operation of the PSU, since the fan does not spin at low loads, add points to the final rating. It may have a high price but you get what you pay for and strangely enough is 17$ cheaper from the identical Seasonic X-850. If in all above you add the seven years warranty that Corsair gives with it then the AX850 looks like a pretty good investment.
To sum up, if you need a tier#1 PSU with great efficiency, silent operation, two hi-end VGAs support and long warranty and you can afford its price then you should definitely check Corsair AX850. Now if you are an extreme gamer and have three hi-end VGAs under the hood there is a bigger brother in the AX series that can easily handle the task, the AX1200. More about this PSU in the near future!