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Will a "Corsair Powersupply 750W" run two 3870x2 in crossfire?

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February 20, 2008 3:24:11 PM

Will a "Corsair Powersupply 750W" run two 3870x2 in crossfire?

cant find any info about this anywhere :( 
February 20, 2008 3:30:50 PM

Under load a single 3870x2 consumes 270-290W. Idle is around 140W.

290W x 2 = 580W

As long as your PC can function on the remaining 170W, you'll be ok. I'm also pretty sure Corsair rates their PSU's as a constant draw as opposed to the peak.

As of now, I wouldn't recommend stressing the PSU like that. You're basically trying to run 4 GPU's off 750W. Tri-SLI with Ultra's recommends at least 1KW (Although, it can be done a 850W PSU).

List your specs for a more definitive answer.
February 20, 2008 6:36:47 PM

4gb DDR2 BallistiX PC8500

CPU: E8400

Mobo: Asus Maximus Formula, X38

Corsair Powersupply 750W

Western Digital Raptor 150GB

Seagate Barracuda 500GB

Sapphire Radeon HD 3870X2
Related resources
February 20, 2008 6:59:35 PM

more about the PSU please...if it cant push the amps, it wont run
February 21, 2008 2:40:08 AM

Well the E8400 will save some power as it uses very little. I would almost suggest an upgrade to 850w just to be on the safe side but it might work.
February 21, 2008 6:27:21 PM

rgeist554 said:
Under load a single 3870x2 consumes 270-290W. Idle is around 140W.

290W x 2 = 580W

I'm not sure where you are getting your info but it's a bit off. Our PSU guy working with ATI has already gotten Crossfire certification with these cards and the TX-750. ATI should have this posted soon. These cards will draw a MAX of 200w and is comparable in overall power draw to an 8800GTX. This PSU will run your system just fine.
February 21, 2008 7:04:38 PM

Quote:
I'm not sure where you are getting your info but it's a bit off.

I found that information here: http://www.anandtech.com/video/showdoc.aspx?i=3209&p=12

This site claims similar idle wattage, but reasonably higher consumption under load: http://arstechnica.com/reviews/hardware/ati-3870x2-revi...

*edit* More:
http://www.tweaktown.com/reviews/1279/17/page_17_power_...
http://www.extremetech.com/article2/0,1697,2252578,00.a...

There was another place with similar results, but I don't appear to have it bookmarked. If it's incorrect you may want to have them correct it for you.

*edit* That's great if it runs of the 750W Corsair. Just voicing concerns based on the information I've gathered. :p 
February 21, 2008 8:05:07 PM

Quote:
Source please??
My post right above yours. Four separate reviews.

If you want another source, here's 5: http://www.tomshardware.com/2008/01/28/ati_r680_the_rag...

That's straight from this site as well. Maybe they are all wrong, but based on the information I've seen / gathered one could see why I posted my comments above.
February 21, 2008 8:45:07 PM

You'd be hard pressed to put together a system that could overload a TX-750. I'm not saying it can't be done, but it would be difficult without tri-SLI.

That being said, PSUs tend to be most efficient at ~40-60% load. A power draw of 600W would put a TX-750 at an 80% load. Corsair most likely underrates their PSUs a bit, but you may still want to consider a higher wattage model.
February 21, 2008 8:52:26 PM

Quote:

That being said, PSUs tend to be most efficient at ~40-60% load. A power draw of 600W would put a TX-750 at an 80% load. Corsair most likely underrates their PSUs a bit, but you may still want to consider a higher wattage model.
If it's anything like the Silencer 750W Quad - It should have a peak output of around 850W. Even if the 3870x2 does only use 200W under load, that would be 400W + Proc, HDD, Fans, SC, etc. That would probably put him right in that 600-700W range (esp. if overclocked) and begin to put the load into the 80% mark as you mentioned.
February 21, 2008 8:54:39 PM

For what it's worth, here's the list of certified AMD power supplies for two 3870x2 and 2900xt:

http://ati.amd.com/technology/crossfire/buildyourown2.h...

Why don't you wait till the 4870 for a second card? The 3870x2 is great for now, but the $299 card reported at Nordic Hardware as arriving in June will be just as fast, then there will also be a 4870x2 @ $499. Hope they arrive on time.

I just installed my single 3870x2 today with an Antec Neo 650 in an Antec Nine Hundred case. I'm downloading 3DMark 06 now to start benchies. I'm using the latest catalyst drivers off ATI's site.

This fall, I'll give CrossfireX a try. If you do go with 2 3870x2's now, let us know how it benches.

February 26, 2008 7:05:42 PM

290w is almost impossible to deliver safely to a video card. Consider that the slot gives a MAX of 75w, a 6 pin cable a MAX of 75w, and an 8 pin connector can supply a MAX of 150w. Trust me, those cards are nowhere close to 290w.
February 26, 2008 7:07:06 PM

rgeist554 said:
Quote:
I'm not sure where you are getting your info but it's a bit off.

I found that information here: http://www.anandtech.com/video/showdoc.aspx?i=3209&p=12

This site claims similar idle wattage, but reasonably higher consumption under load: http://arstechnica.com/reviews/hardware/ati-3870x2-revi...

*edit* More:
http://www.tweaktown.com/reviews/1279/17/page_17_power_...
http://www.extremetech.com/article2/0,1697,2252578,00.a...

There was another place with similar results, but I don't appear to have it bookmarked. If it's incorrect you may want to have them correct it for you.

*edit* That's great if it runs of the 750W Corsair. Just voicing concerns based on the information I've gathered. :p 

Check your Anandtech link again. That 290w is for the entire system power draw. Not just the card.
February 27, 2008 12:05:33 AM

XMSYellowbeard said:
290w is almost impossible to deliver safely to a video card. Consider that the slot gives a MAX of 75w, a 6 pin cable a MAX of 75w, and an 8 pin connector can supply a MAX of 150w. Trust me, those cards are nowhere close to 290w.


So under max load a total combined power amount of 300w(75+75+150=300) wouldn't be enough to give the card 290w? Its possible.

I don't doubt it can get that high in power usage. 2 chips on one PCB. Now imagine the ones that will come stock OC'ed/ Probably use more power. I wounder how OverDrive will work with that card?
March 1, 2008 9:01:24 AM

Hey will a p35 mobo support crossfire x cuz i'm getting a pc with hd3870x2 and am interested in crossfiring it with the hd4870x2. If not how much more will a x38 mobo cost?
March 1, 2008 10:09:16 AM

The simple answer: YES
March 1, 2008 10:41:24 AM

jay2tall said:
The simple answer: YES


My God, Why were there not more answers like that.
The 750w Corsair will not even be pushed that hard.
March 1, 2008 1:40:28 PM

zenmaster said:
My God, Why were there not more answers like that.
The 750w Corsair will not even be pushed that hard.

I did notice there were no other simple answers. And I know sometimes all I want is some reassurance in that manor.

The Corsair PSU's are really nice and can handle a good bit. no two PSU's of the same wattage are create equial. There are 750W and there are 750W. I think those as 52A on a single rail.
March 2, 2008 8:07:48 PM

zenmaster said:
My God, Why were there not more answers like that.
The 750w Corsair will not even be pushed that hard.


Because life is not all zen. Even Zen is not all zen, in the sense of the New Age slang term meaning simplicity.

We can assume that a 750 watt PSU will run any two cards, but the caveat is that it has to be a quality PSU. certified by AMD for that purpose.

Me, I checked ATI's list, and then after confirming his PSU was on that list; I discussed the upcoming 4870 and 4870x2's that were also of interest to him. He may not have seen the Nordic Hardware article.

Besides, there are people who would answer "yes" if he'd asked about a Rosewill (bad idea), or "no" if they were convinced that what one "really" needed is a 1000 watt Antec TPQ.

Sometimes in life it's better to be a journeyman in complexity than a master in simplicity.
March 2, 2008 8:34:32 PM

Corsair has pretty much the same specs as the PC Power and cooling 750 Silencer, and that PSU will handle your build easily.

So I think you will be find. PS it has a single 60amps on a 12v rail. It's a good design.
March 2, 2008 8:51:31 PM

yipsl said:
Because life is not all zen. Even Zen is not all zen, in the sense of the New Age slang term meaning simplicity.

We can assume that a 750 watt PSU will run any two cards, but the caveat is that it has to be a quality PSU. certified by AMD for that purpose.

Me, I checked ATI's list, and then after confirming his PSU was on that list; I discussed the upcoming 4870 and 4870x2's that were also of interest to him. He may not have seen the Nordic Hardware article.

Besides, there are people who would answer "yes" if he'd asked about a Rosewill (bad idea), or "no" if they were convinced that what one "really" needed is a 1000 watt Antec TPQ.

Sometimes in life it's better to be a journeyman in complexity than a master in simplicity.


You definitely added some useful information, but all of the answers did not give a clear answer to a simple question. I often find it best to answer to provide a simple answer first and then provide details later to support that answer. This way those who can't understand the explanation will not miss the answer.

!