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Author Topic: Ideas on Crossfiring 2 Radeon 7970's?  (Read 1256 times)
Meatball
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May 16, 2012, 10:02:07 PM
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So, here's my situation, I recently picked up a Sapphire Radeon 7970 OC edition on Newegg for $449 to replace a pair of 6950's I had set up in Crossfire.  Card worked out great and I can easily OC it to 1100/950 and get a bit over 650 MH/s out of it at a decent 73C.  I decided to pick up another one and Crossfire them and get some extra hashing in.

I have a MSI Big Bang Fuzion board that has 3 x16 slots in it, and this is my main machine, so everything has to stay tucked nicely in the case.  So, with these 7970's, the fans are mounted on the side of the fan enclosure, but the enclosure is a bit wider than 2 slots, so if I try to Crossfire them, the 2nd card blocks the intake of air on the 1st and it shoots up to 85C+ in 10 or 15 seconds and appears to want to keep climbing even at 100% fan.  I've tried to put them in the 1st and 3rd slot, but the dang distance is longer than the 100mm Crossfire bridge they supplied will reach and I can't for the life of me find anyone that makes/sells any bridges bigger than that.

So, anyone know of somewhere that has longer Crossfire Bridges or have any other thoughts?
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May 16, 2012, 10:23:16 PM
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Just use a longer crossfire cable.  eBay has them.

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May 16, 2012, 10:28:28 PM
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I'm guessing you want the crossfire for gaming or something else? Because you don't need crossfire to mine as it has zero influence on hashrate.

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May 17, 2012, 01:06:50 AM
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Noone that I've found makes crossfire cables longer than 100mm.  Those are the ones I have and came with the cards, and they're not long enough. 

As for the Crossfire, yeah, I'm using them in my main machine which is mostly for gaming.  I know it doesn't matter for hashing, but it's in there, I might as well use it.
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May 17, 2012, 01:19:12 AM
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I don't know how tedious the latency issues with xfire are, but you could modify it yourself. Else you could take two cables and find an extender, or m-m xfire plug fir them.

If that fails, cutting holes for two fans blowing directly between the cards will help, plus you can stick something between the cards separating them a bit.

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May 17, 2012, 01:56:39 AM
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If you are mining, may I suggest that you water-cool those cards? You can earn back the $100 it takes for the block in about 2 years of 24/7 mining due to the lowered leakage from the lower temperatures.

See this thread.


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