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Quadi Sli/Quad Fire PSU - 850W good enough???

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February 11, 2009 1:52:17 PM

Tom's did a quadi sli/ Quade fire review with the 295 and 4870x2, they used an 850 Watt power supply - including water cooling. WTF.

http://www.tomshardware.com/reviews/geforce-gtx-295,212...

I know it all about the amps on the 12v rail etc., but still. Used a calculator to estimate power requirements for a 295 in sli, 4 HDD, OC'd i7, et al, all running at 90%, with 95% tdp and it estimated I need 830W. Now I know if wont be good to push an 850w with that for a long time, but will it do? For example the Corsair 850, will it give consistent 850, cause that will do me fine. The other problem is that there is a coolermaster 1000W, but it has SIX (6) 12v rails. The problem is that a 295 will take about 300W, which a single rail wont be able to provide. Whats the solution, besides splurging and buying a really expensive PSU. Please help!

More about : quadi sli quad fire psu 850w good

a b ) Power supply
February 11, 2009 4:10:22 PM

Well, 830 is less than 850... The calculator gives you recommended size, not power consumption. And the number of rails does not matter.
February 11, 2009 5:31:01 PM

So please someone confirm this for me. Does the number of rails NOT matter. If a PSU has 1000W and 20 rails, it wont affect anything?

And also what's the difference between recommended size and consumption? Why is there any need for PSU's even as big as 1KW when a quadi sli, multi HDD, OC'd i7 set up only require 830???
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a b ) Power supply
February 11, 2009 8:50:25 PM

faridakoi said:
So please someone confirm this for me. Does the number of rails NOT matter. If a PSU has 1000W and 20 rails, it wont affect anything?

And also what's the difference between recommended size and consumption? Why is there any need for PSU's even as big as 1KW when a quadi sli, multi HDD, OC'd i7 set up only require 830???


If it had 20 rails it would obviously matter.

Why does the video card need to draw all of its power from one rail?
February 11, 2009 8:54:10 PM

1) Gpus dont use near as much power as they say they do

2) As long as u use connectors based off different rails, 99% of the time ull be fine. Most PSUs just use a fake way to split the rails from 1 source. Something different is the HX 1000 cause its basically 2 PSUs in 1 so 2 rails
February 11, 2009 9:38:38 PM

Thanks guys, I find that there is so little info about this on the net. I figured it out from a review on the coolermaster which had 6 rails. No one mentions that the set up of wires coming out of the PSU are designed so that the 6/8 pin pci-e connectors get the lion's share of the amperage. But I'm still confused by why there are massive PSU's when the most demanding set ups draw 150-200 watts less than required at full power? The most baffling are set ups when a guy will have a STANDARD machine, with a single card (i.e. single GPU, e.g. GTX280) and will be using a 1000W PSU. I understand that some of those guys must be preparing for future SLI/Xfire, but I don't believe that everyone is. Anyway, just to confirm - not that I am getting THAT one - but when a power calculator tells you that at peak you will need 830 Watts, it is doable to be using a good 850W PSU? thanks.
February 11, 2009 10:05:11 PM

What i dont get is how did u get 830watts on a calculator. I just quickly plugged in ur build and get around 700...
February 11, 2009 10:10:24 PM

Silverion77 - I used this calculator - http://extreme.outervision.com/psucalculatorlite.jsp
Can't link the set up, but here it is.
Core i7 - 920 Oc'd to 3800MHZ @ 95% TDP
'High end' mobo
6 Dimms DDR3
2 GTX295
3 Sata HDD
3USB Devices
1 Firewire
1 Blu ray drive
1 DVD drive
1TV tuner
1 120mm fan
2 80mm fan

All the above running at 95%


February 11, 2009 10:15:59 PM

U should be perfectly fine with a 850...Especially if its a high-end PSU (cough Antec Signature, Corsair, Seasonic cough)
All calculators overshoot
February 11, 2009 10:19:06 PM

Thanks Silverion, but do you think that there is a risk in running at near those settings for a long time? I know that it is highly unlikely that I will blazing 3 HDDs, 2 optical drives and 2 GPUs all the time, but what is undesirable is to have a system fail on me, when 30 pounds extra would get me 1000 watts.
But more fundamentally, WHY do people buy crazy PSUs? Why do they even exist??? I mean, I can see how you can approach using 1000 watts, but never 1200/1300??!!!!
February 11, 2009 10:21:25 PM

Also, why do houses such as Nvidia and ATI only recommend MASSIVE PSUs? If you go on to Slizone, I dont think they recommend anything under 1200 watts for a 295sli.
February 11, 2009 10:23:42 PM

Big PSUs?? Cause they can...bragging (lol) or just plain seeing a big PSU.
As for Nvidia and ATI...same reason^^^

Its better to get a good quality psu vs. just a big one.
February 11, 2009 10:27:17 PM

Can I just ask you straight up then, what do you recommend a 850 Corsair or a 1000 Coolermaster? they are the same price here in the UK. Or if you know of a 'perfect' PSU that fits those requirements?
February 11, 2009 10:28:59 PM

Also, just from your settings, would you get a new PSU if you hypothetically decided to get another GX2?
February 11, 2009 10:29:05 PM

Corsair is just a better build than CM and would choose Corsair above the CM anyday.

I would only get a bigger PSU as long as u dont give up quality.
!