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ATI Radeon 4870 in Crossfire power setup?? HELP!

Last response: in Graphics & Displays
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January 29, 2010 3:55:27 PM

greetings, love toms of course. now for the question.

I just got my other 4870 in the mail today. im in the process of connecting it up so i can run STAR TREK ONLINE in CROSSFIRE mode :)  . i have a few questions about connecting the power up.

how do i best do this? i just bought a OCZ ModXStream Pro OCZ700MXSP 700W ATX12V V2.2 / EPS12V SLI Certified CrossFire Ready 80 PLUS Certified Modular Active PFC Power Supply.

now each video card has 2 x 6pin power connectors. my new power supply only has 2 6pin connectors, so the video cards came with adapters. that look like this:









So i am guessing that i will take 2 of those and use them. now my main question is this. looking at the power adapters do i plug in 2 power cables into it? or just one? i dont want to over power anything. and i also want to know if i need to connect power to both the power ports on the video card or not. JUST NOT SURE WHAT TO DO!

THANKS GUYS!

a b U Graphics card
January 29, 2010 6:38:30 PM

First if you have the ability to return that OCZ PSU I would, and get one that has atleast 4 of the needed 6 pin power connectors.

If not then its not the end of the world. Use the adapters and connect all 4 6 pins to the cards. Note* spread out the load on those 4 pin molex's to seperate leads on the PSU for best results.
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January 29, 2010 7:52:41 PM

I agree with paperfox,i am running the same cards and its always best to use the correct connectors in regards to crossfire/sli,but i cant see how your PSU can be CF ready if it only has 2x6 pin connectors,i am sure that most modern cards now have two of those plugs so a CF/SLI PSU should come with minimum of 4x6 pin connectors.
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a b U Graphics card
January 29, 2010 7:58:13 PM

Yes, two molex (4-pin) plugs equal one 6-pin plug. So you will need to plug all four molex plugs in to power your cards.

The 4870 DOES need both power plugs, so don't try to make do with one.

Yes, ideally, you would be using a different power supply with the right connectors; this is kind of jury-rigging it but it should work.
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a c 106 U Graphics card
January 29, 2010 8:08:45 PM

Should be O.K with that PSU, but it's not ideal. I also agree with Paper Fox, but assuming you can't return that PSU then use the adapters.
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a b U Graphics card
January 29, 2010 8:11:30 PM

andy_93 said:
I agree with paperfox,i am running the same cards and its always best to use the correct connectors in regards to crossfire/sli,but i cant see how your PSU can be CF ready if it only has 2x6 pin connectors,i am sure that most modern cards now have two of those plugs so a CF/SLI PSU should come with minimum of 4x6 pin connectors.


It SHOULD come with four 6-pin connectors, but technically you can still use it for crossfire -- just not with the really good cards. You could crossfire 5770s, 4850s, GTX 9800s ... things like that. So if they can call it a crossfire PSU, I'm sure they'll go for it just to help them sell more.

What seems sillier to me is that they would make a 700W PSU with only two 6-pin connections so most people can never actually USE all the power.

I mean, I guess you could, if you were liberal about using adapters or you had, like, 5 hard drives that were always spinning. But for 90% of people, that thing is going to be sitting at half capacity because that's all the cables there are.
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January 29, 2010 11:03:58 PM

My PSU is a 1000watt but still only comes with 4x6pin connectors so i can only go 2xCF,but it is possible to go quad,so are there PSU`s out there with 8x6 pin connectors?
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a b U Graphics card
January 29, 2010 11:10:42 PM

Newer PSUs have up to six/eight 6pins, better yet 6+2pins that can be used as either 6 or 8 pins as needed for maximum flexibility.
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January 29, 2010 11:30:01 PM

thanks guys.. do i use both the CROSSFIRE BRIDGES? there is a video on amds website that says u do. HELP!
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a b U Graphics card
January 30, 2010 12:43:52 AM

both, yes. tho i think some people can get away with just one.
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January 30, 2010 9:33:16 AM

I only use one,i have read many forums on this,i did use two but most reports say that only one is needed.
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