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6850 cf x8/x8 or 6990?

post #1 of 43
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Sorry Forum experts I need some advice.

I was all set to crossfire my 6850 when I discovered that my mobo only supports cf at x8.

I talked it over with the boss (wife) and I have 2 options.

1. stick to the plan - cf 6850 - but at x8.

2. Get a 6990 - but I gotta wait - shes offered one (when bf3 comes out in oct) as a kinda late bd/early xmas gift deal.

What should I do?
Is x8/x8 a no-no?

Cheers in advance guys.
    
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post #2 of 43
You may see some improvement if it was x16/x16 but not much honestly. if your getting the desired performance your fine. Ok i just reread and saw that you havent gotten them yet. In that case i would get the 6990. if you dont want to wait you can get another 6850 and cf them. You wont see that many problems with x8/x8
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post #3 of 43
Crossfire the 6850 assuming the monitor you're using is the one in your sig. There's virtually almost no performance decrease in going from x16 to x8 in dual-gpu configurations. Will look for that test which demonstrates it, I think it's from Tom's or HardOCP.
Edited by goldcrow - 5/30/11 at 8:27am
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post #4 of 43
8x is only 5% (at the maximum) slower than 16x
but 6990 is faster than 6850x2
in my opinion get another one, cause u can max out almost every game with those
waiting till october is pointless
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post #5 of 43
There is virtually no difference in performance between x8 x8 and x16 x16 configurations. Check this review out: sli gtx 480s x16x16 vs x8x8

http://www.hardocp.com/article/2010/08/23/gtx_480_sli_pcie_bandwidth_perf_x16x16_vs_x8x8/

considering that 2 6850s cost pretty much half of 6990 price - i'd go that route. 6990 obviously faster but not twice as fast:

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post #6 of 43
Tomorrow sucks. Get the 6850 and crossfire them.

Or suggest a compromise, you get your 6990 now and she gets what ever you were thinking of for her for Christmas. Another thought is to offer to do something she knows you dislike, a weekend at her parents place?
Edited by Spct - 5/30/11 at 1:47pm
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post #7 of 43
if you're thinking of eyefinity in the future, the 6990 will take care of you. If not, its a huge price leap and xfire 6850 makes better sense for your resolution and cost.

edit: better cost effective eyefinity is crossfire 6950 2gb.
post #8 of 43
In my experience my dual 5850's out perform dual 6850's.
(I'm lucky, I didn't get SandyBridge, so I run at 16x+16x)

The 6990! WOAH!! Me Want!

An HD 6990 kinda blows away the Crossfired 5850's/6850's.

I would kill, yes, kill for a 6990.
post #9 of 43
6990. It wipes 2 6850's away. If it was two 6950's I would say yes but since its the 68XX series im gunna have to say wait for the 6990 man,and then you can sit on that card for a good 2-4 years iwthout any upgrade.
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post #10 of 43
I'm running CF6850s on x8/x8 and loving it. Heat and noise are an issue, but that's true of all crossfire setups. Somebody up there posted the difference on SLI 480s and it was minimal. I'd wager the 6850s don't see as much difference either, simply because they aren't taking up as much bandwidth as 480s.
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