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Same speed with CrossfireX

Last response: in Overclocking
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October 22, 2011 4:31:28 AM

What the freak?! I just got a second 5850 to run CrossfireX. With 1 video card I got a PCMARK7 score of about 3378 and with both installed I got 3414. I know they are both installed correctly, the bridge is installed, CCC detects both cards, I have Enable AMD CrossFireX selected, rebooted and everything. I have the latest CCC installed. I cant figure it out. Do I need to change something in the BIOS? I have the BIOSTAR TZ68+. Any help would be greatly appreciated!

More about : speed crossfirex

October 22, 2011 5:16:53 AM

Could it be my psu? I think its 650 watts, maybe not enough power? Should I plug the second 5850 into a port leading from the psu?
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October 22, 2011 5:20:26 AM

My motherboard has PCI Express x16 and x4. Can the x4 keep the second card running slow?
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a b U Graphics card
a c 190 K Overclocking
October 22, 2011 2:14:43 PM

Sorry for lack of answers but yes, your x4 lane is the issue there
and I'm unsure of the power req's for the 5850 but I think the psu may be contributing, although the slow lane is the major problem you have
Moto
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a b U Graphics card
a c 183 K Overclocking
October 22, 2011 2:33:01 PM

A quality 650W psu is fine for 2 x 5850.
As Moto said a x4 slot isn't ideal.
That's why folks buy certified sli/xfire boards.
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October 22, 2011 8:28:23 PM

I just checked and motherboard and psu are both CrossfireX certified, so hopefully thats not an issue. I ran 1 card in Bad Company 2 and recorded the fps in certain areas and then I ran it in CrossfireX and recorded the fps in the same areas. Luckily the CFX seems to be working because the fps went up by at least 1.4x and up to 1.9x in some areas. So maybe the trial version of PCMARK07 that I have doesnt support CFX or something? Hopefully CFX will really help with Battlefield 3!
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a b U Graphics card
a c 190 K Overclocking
October 22, 2011 8:32:20 PM

Possibly theres that limitation on a freeware version, at least you seem to have figured things to your satisfaction though,
let us know how Bf3 turns out for you :) 
Moto
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