Radeon HD 6870 Trifire possible?

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Radeon HD 6870 Trifire possible?

Postposted on Thu Aug 22, 2013 10:06 am

Hello all, (first post here, be nice please, Thanks)

I own an XFX 6870 (dual fan edition, woot) and I have also purchased a second 6870. The strange part about it though, is that it has no branding manufacturer other than ATI (or AMD, I forget at the moment). It's very long board, has a full size displayport connection (not through an adapter, literally on the card instead of two minis) and it has TWO CROSSFIRE fingers. I don't currently own a third 6870, but I was wondering if it would function in Tri fire (assuming a standard crossfire cable and a long one would work together to get the strange setup to work as described below) or if the fact that this seems to be a freak card would have issues with drivers and would be a waste of time and money to try to acquire a third card. Thanks for the assistance

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Standard cable here between left two (above and below)
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long cable from right finger of above to left on card below
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Kairu43
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Re: Radeon HD 6870 Trifire possible?

Postposted on Fri Sep 13, 2013 2:13 pm

Well I think the primary issue you would run into is whether your motherboard has 3 pcie slots to put those cards into. Chances are that you have 2 pcie-8x/16x slots then one pci-e 4x (or 1x), which would more than likely cause problems with the setup, if it worked at all.
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Re: Radeon HD 6870 Trifire possible?

Postposted on Fri Sep 13, 2013 2:23 pm

Aside from the likely low PCI-Express bandwidth on the third slot, you'll probably find that you're running out of graphics memory on a 1GB 6870. You'd have the fillrate and shader power of three cards but you'd still be limited to whatever graphics settings run well on a 1GB card - in other words you'd get better framerates at the same settings but you'd never get good perfomance on Very high or Ultra.

Multi-GPU setups suffer from running out of memory even more than single cards because they have to share the PCI-E bus with other graphics cards, which adds latency to memory fetches from outside of their dedicated VRAM.

When you start to come across games that struggle on a two-card setup, it's time to sell both cards and buy something newer
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Re: Radeon HD 6870 Trifire possible?

Postposted on Fri Sep 13, 2013 4:55 pm

Possible? Yes. A good idea? No. The scaling from two cards to three is much less than the scaling from one card to two(And three cards to four? Might as well not bother). You'd be wasting money for all but a few things.
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Re: Radeon HD 6870 Trifire possible?

Postposted on Fri Sep 13, 2013 11:09 pm

Fortunately, I just recently upgraded my motherboard to an Asus z87-ws which is fairly friendly with multi-gpu setups. I see your points though. If I could get one cheap enough, I'd still be interested in trying it, but chances are I'll upgrade before I find another 6870 at a cheap enough price to make that jump. Thanks everyone!
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Re: Radeon HD 6870 Trifire possible?

Postposted on Sun Sep 15, 2013 9:27 pm

Many of us have tried multi-GPU configs in the past. I had quite a lot of experience with them up until a couple of years agi; Provided you are okay with tinkering, you can get them to work reasonably well, but I just got sick of having to tinker.

My advice is to change your attitude to upgrades; Rather than looking for a cheap second card, look for how much you can expect to sell your existing card for, and offset the price of an upgrade by that much. When the new generation of AMD cards comes out, I'd be expect a load of 7800 and 7900 cards to hit ebay.
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