PSU: 750w vs 850w, which would I need?

Space Monkey

Space Monkey

Space Monkey

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Hi guys,

Looking at getting either the 750w or 850w Corsair AX PSU, just need some confirmation on which is the best for my setup?

i7 3770K
Gigabyte Z77X - UD5H WIFI
GTX 480
16GB RAM
2 x 1TB hard drives
1 x SSD
DVD RW
3.5" Card Reader / USB hub
3 x 180mm fans
1 x 120mm fan
And the CPU & GFX will be water cooled

(CPU and GFX will be overclocked)

Would the 750w be 'just' enough or a 'woah, bro you could park 10 double decker buses in there enough' :D or should I get the 850w as it's about £17 more?

TIA :)
 
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If you're spending that sort of money anyway I'd go for the 850w, another £17 isn't going to be noticed but a more powerful PSU might last longer before you need to upgrade it.
 
You ever intend to SLI then 750W is all you will ever need, going over can actually be a bad thing as the PSU will be less effecient.

If you are never going to SLI then 550W is plenty, if you are going to SLI but not the top end cards then 650W will be fine.

850W is just over the top.
 
Bacon? said:
You ever intend to SLI then 750W is all you will ever need, going over can actually be a bad thing as the PSU will be less effecient.

If you are never going to SLI then 550W is plenty, if you are going to SLI but not the top end cards then 650W will be fine.

850W is just over the top.
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As long as it's around 40/60% load then it's not really an issue.

If you're system is pulling around 400w then the 850w might be a better option because you're closer to that 50% efficiency sweet spot.
 
The larger AX should be quieter at both idle and load.

PSUs do lose effeciency with age. Going over spec is always a good idea if you plan to keep the PSU for many years.
 
sadbuttrue said:
The larger AX should be quieter at both idle and load.

PSUs do lose effeciency with age. Going over spec is always a good idea if you plan to keep the PSU for many years.
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thats true,ive just had to rma a 400w for the same reason,thinking i was clever and could get away with a lower wattage,turned out it was working much harder and fan was spinning faster to cool psu ect,i ordered a 600w of the same model/brand and its much much quieter due to it not working so hard
 
I would get the 850 - personally I have just had to spend extra upgrading my 600w OCZ as I skimped a bit when putting my phenom x6 build together and now I want to try crossfire 6950's (flashed to 70's). Its always nice to have the option to upgrade and a decent PSU can be recycled for your next builds.
 
I'm confused at his comment wronging the idea of efficiency.

Try get the one which has the best efficiency for the power point that you will be using, as well as weighing up any possible future upgrades. I would say that the 750W should be enough for any future SLI upgrades.
 
Bacon? said:
Can you please stop sprouting trout.
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The guy was not 'sprouting trout' he was quite accurate!

The slight efficiency increase only earns you a couple of quid off your yearly electricity bill though (and a slight temperature increase within the psu with that wasted energy :rolleyes:)
 
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