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Old July 29, 2011, 11:23 AM
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Default 6950 crossfire 16x/x4 bad?

So im thinking of going crossfire 6950's but the only thing that is stopping me is that my motherboard only supports 16x/x4 crossfire..so what i want to know is how much performance will i lose and is it worth it?im gaming at 1600x900 yes,yes,i know overkill..I KNOW!!
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Old July 29, 2011, 12:56 PM
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I wouldn't cross fire x16 /x 4 only x8 /x8 and above
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Old July 29, 2011, 01:08 PM
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At that low resolution, I wouldn't recommend it as a decent upgrade at all. If you plan on upping your resolution, thats a different story.
According to toms, the 6950 at x4 will get anywhere from 25 to 50% less performance then at x16, depending on resolution. What motherboard and cpu are you using?
http://www.tomshardware.com/reviews/...ce,2887-6.html

Also, make sure you board has a x16 physical slot wired for x4 electrical, and not just a x4 physical slot, otherwise the card won't fit.

You may want to check out some pcie scaling articles for further reading:
*Asus P8P67 (PCIe 16x/4x) vs. Asus P8P67 Deluxe (PCIe 8x/8x) - HD6950s in CF tested* - AnandTech Forums
GTX 480 SLI x16/x16 vs. x4/x4 - GTX 480 SLI PCIe Bandwidth Perf. - x16/x16 vs. x4/x4 | [H]ard|OCP
http://www.tomshardware.com/reviews/...x4,2696-3.html
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Old July 29, 2011, 01:51 PM
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It was bad when I tried it with 3870's years ago. (and a pair of 6800GS's long before that )
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Old July 29, 2011, 05:23 PM
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Quote:
Originally Posted by bcall12 View Post
So im thinking of going crossfire 6950's but the only thing that is stopping me is that my motherboard only supports 16x/x4 crossfire..so what i want to know is how much performance will i lose and is it worth it?im gaming at 1600x900 yes,yes,i know overkill..I KNOW!!
No such thing as overkill. Using 16x/x4 for crossfire is pure stupidity.

Let me put it this way, why would you pay for 2 expensive gpu and cheap out on a board that can't bring out the cards true potential?


You probably won't lose performance depending on the game, but extremely small gain using 16x+x4 PCIE lanes.


Time to upgrade motherboard board, or go 6990.
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Old July 29, 2011, 06:17 PM
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You'll probably net better overall performance going with two lesser cards.
I would not suggest using what you want to use on a board that only offers those lanes, you would really be choking the second card.


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Old July 29, 2011, 07:02 PM
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just get one 6950 and see what gives.

welcome aboard btw
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Old August 1, 2011, 03:02 PM
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http://www.hardocp.com/article/2010/...x16x16_vs_x4x4
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Old August 1, 2011, 05:40 PM
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Quote:
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That is done on a X58.

Most mother board that support X16 + X4 are budget board , the X4 lane been controlled by the chipset. What good will do you by adding extra latency between cpu and gpu? A good headache from the Micro Stuttering.


But don't take my words for it, best way to find out is to experiment.




A much much better scaling review.


AMD Radeon HD 5870 PCI-Express Scaling Review - Page 1/26 | techPowerUp
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