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Corsair AX750 VS AX850

Hi,
Here are the core component of my next build

Mobo : Asus P8p67 Deluxe
CPU : i5 2500k ( will OC moderately )
Heatsink : Noctua NH-C14
Ram : 2x4gb G.Skill Ripjaw X
GPU : Asus GTX 570 DirectCU II
Storage : 1 c300 ssd + 2-3 HDD ( i have 1 wd caviar black 1tb and 2 older wd drives, might not use )
Case : not sure yet, choices are bitfenix survivor, lian li PC-7NF...

I am aiming for a performance build that can be as quiet as possible, this is why i am going with the corsair AX series psu, however im not sure which one to get... I know the AX750 will be enough power, however, the way the PSU work is that whenever it is bellow 20% of max load, the fan doesnt spin at all, it is in silent mode. When the load is between 20-50% , the fan is in constant speed "quiet" mode, and then above 50% the fan speed will go up according to load/temps ( i call it noisy mode ).

So goal here with going with the 850 instead of the 750 is to avoid reaching above 50% load and possibly keep my system under the 20% to be in complete silent mode, however im not sure that is even possible.

I dont plan on ever going sli btw, so i know 850 is overkill, this is strictly based on noise reduction. If both system are going to be in "quiet" mode ( under 50% ) most of the time, then there is no point in paying an extra 20$ or so for the 850...
8 answers Last reply Best Answer
More about corsair ax750 ax850
  1. What are you going to cool the GTX570 with? That looks to be the loud part of your system and will certainly be louder than a high quality PSU like the AX!
  2. I aint doing anything, the Asus GTX 570 DirectCU II seems to be the most quiet 570 out there... i know this will likely be the loudest part in my system, but what can i do... The only other option would be to go with a GTX 560 Ti , but this will affect performance too much i think...
  3. I do not think it matters much between the two GTX's. On the PSU's you sacrifice efficiency running it at low loads http://www.corsair.com/power-supplies/modular-psus/professional-series-gold-2/ax850.html highest around the 50% mark the noise is 40decibels at full load which happens to be the same as the Asus card http://www.techpowerup.com/reviews/ASUS/GeForce_GTX_570_Direct_Cu_II/22.html
    I would just get the smaller PSU!
  4. Well, Acutally , the Asus DirectCU II at maximum fan speed is supposed to be about 31db , linky

    ... so.. do i still get the 750 ?
  5. so essentially youre saying that my build as is, in idle or light usage should remain at least within the 50% load of the 750W psu, therefore the psu should never need to go into its active cooling phase ( above 50% ) ?
  6. Best answer
    What I am saying even if you put a heavy load on the PSU it will not go to the 650watts that would exceed the 31db your GPU is putting out at the same time. Your max loads (+ additional drives which is not much) under normal use would be according to this 361watts and stress test 446watts http://www.anandtech.com/show/4209/amds-radeon-hd-6990-the-new-single-card-king/18
  7. Best answer selected by louno.
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