Will this power supply be adequate for two 5870's in crossfire?

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bazookajoe19

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#1 bazookajoe19
Member since 2006 • 827 Posts

http://www.newegg.com/Product/Product.aspx?Item=N82E16817153106

Eventually I would like to add a second graphics card. I'm not even sure if I will be getting a 5870 for my build but it is very likely. I'm assuming this would not be adequate for two 480's in SLI because of their ridiculous power consumption.

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GhoX

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#2 GhoX
Member since 2006 • 6267 Posts
That should definitely be enough. Two 5870(overclocked) use less power than even 470 SLi.
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smc91352

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#3 smc91352
Member since 2009 • 7786 Posts
yes:[spoiler] . [/spoiler] [spoiler] this is not a 1-word post [/spoiler]
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04dcarraher

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#4 04dcarraher
Member since 2004 • 23858 Posts

Yes the psu is enough for 5870 in xfire. And its plenty for GTX 480's in sli also. People over do the heat+power bit for the GTX 400's

You can run SLI'ed GTX 480's on a good 750w PSU.

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bazookajoe19

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#5 bazookajoe19
Member since 2006 • 827 Posts

Thanks. I'm definitely buying this psu then. It will only be $80 after the mail in rebate and the promo code.

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ravenguard90

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#6 ravenguard90
Member since 2005 • 3064 Posts

Yes the psu is enough for 5870 in xfire. And its plenty for GTX 480's in sli also. People over do the heat+power bit for the GTX 400's

You can run SLI'ed GTX 480's on a good 750w PSU.

04dcarraher

Oh really? Because the graph SMC posted proves you wrong.

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Obiwan_1O

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#7 Obiwan_1O
Member since 2003 • 286 Posts

what about two 5830s in xf on a 700w psu would that be ok?

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Luminouslight

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#8 Luminouslight
Member since 2007 • 6397 Posts
If you have good 700 watt, I don't see any reason why not.
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04dcarraher

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#9 04dcarraher
Member since 2004 • 23858 Posts
[QUOTE="ravenguard90"]

[QUOTE="04dcarraher"]

Yes the psu is enough for 5870 in xfire. And its plenty for GTX 480's in sli also. People over do the heat+power bit for the GTX 400's

You can run SLI'ed GTX 480's on a good 750w PSU.

Oh really? Because the graph SMC posted proves you wrong.

The GTX 480 cant exceed the PCI-e power limit of 300w which is pci-e slot 75w, 6pin 75w, and 8pin 150w. Nvidia has rated the card to use 250w and even if its 20w more like 270w , two cards would only use 540w and with a normal system would use under 700w.
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ravenguard90

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#10 ravenguard90
Member since 2005 • 3064 Posts

A rate can be made based on the average of the total power consumption of the card. If you factor in the margin of error to that estimation (which seems to be large considering graphs such as the one above), then a 750W power supply would be pushed close to, or even past, its limits at certain points by using GTX 480 in SLi. Here are two other reviews that show that the GTX 480 can very well surpass that 300w threshold. Hexus, techPowerUp.

Overall, GTX 480's in SLi may run on a 750w, but you run the risk of degrading your power supply faster than usual.

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04dcarraher

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#11 04dcarraher
Member since 2004 • 23858 Posts
The card cant surpass the 300w limit , and your sources prove that fact , the techpowerup shows the two cards peaked at 472w in sli, then Hexus dont tell you that their load is "total system load" and the last chart of tech's max power load too. So even if you have a good 750w psu SLI'ed GTX 480's wont be pushing the system as much as you think. If you have a 750w PSU that can supply 90% or more of its wattage through the 12v rail/s you will be fine,
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ravenguard90

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#12 ravenguard90
Member since 2005 • 3064 Posts

I agree with you with Hexus, but Techpowerup's chart for maximum power draw is solely for the video cards only. Just look at the readings of the other cards on the same chart.

Referring to the Hexus review for PSU stress, when the example rig requires 710w for the entire rig, and considering the majority of 750w PSU's are rated at 60A on the 12V rail (720w), that is extremely close to what the PSU can handle. I personally would not feel comfortable leaving such a small cushion of power within a PSU.

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04dcarraher

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#13 04dcarraher
Member since 2004 • 23858 Posts
[QUOTE="ravenguard90"]

I agree with you with Hexus, but Techpowerup's chart for maximum power draw is solely for the video cards only. Just look at the readings of the other cards on the same chart.

Referring to the Hexus review for PSU stress, when the example rig requires 710w for the entire rig, and considering the majority of 750w PSU's are rated at 60A on the 12V rail (720w), that is extremely close to what the PSU can handle. I personally would not feel comfortable leaving such a small cushion of power within a PSU.

The problem with Techpower is that one chart days peak load which means max load at any given time. but for going from 472w to 624w for max load just for the cards is not right, and then their average load is only 20w less then the peak load. For the cards to magically draw an extra 152w is bull. At max the GTX 480 can only use 300w that is that max ouput for a pci-e slot(75w/6pin 75w/8pin 150w). Which is way ATI had to customize the gpu's on the 5970 to stay under the 300w limit. If they were to just use two normal 5850 cores for the 5970 it would have been over the 300w limit. So if we take Nvidia max power usage of 250w and the averages online benchs of around 270w. Two cards would draw 540w then add 170w for a high ended system. PSU's like the Corsair 750TX can supply upto 900w if needed.
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smc91352

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#14 smc91352
Member since 2009 • 7786 Posts
The GTX 480 cant exceed the PCI-e power limit of 300w which is pci-e slot 75w, 6pin 75w, and 8pin 150w.04dcarraher
That's still irrelevant. The chart showed the total system power use (theirs was obviously very power hungry)

The chart showed the highest power draw for (2) 5870s in Crossfire (that I've seen) so I used it...that psu will most definitely power (2) 5870s.

(2) GTX 480s in SLI have used 851W for them; you'd need to see how much you're powering (aside from the graphics card) to see if you can power (2) GTX 480s...