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am3 crossfire boards question

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#1
Ok so i have been looking into purchasing a crossfire board for sometime and i am leaning towards the amd boards for their price/performance ratio in gaming...So I have noticed that a lot of the crossfire boards (especially from gigabyte) have one 16x pci-e slot and one 8x pci-e slot when both are occupied. Could anyone give me an answer to why this is? Also how do these performed when compared to a 8x+8x board? Also if anyone has one of these boards i would really appreciate your thoughts on your board :)
 

Mussels

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#2
they do it with lower bandwidth because its cheaper to make that way.


8x/8x boards wont hurt performance, but 16x/4x boards might.
 

Jakl

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#3
What model of motherboard do you have? Best is to fill out your system specs in your User CP ...

but yea, if you do crossfire, it will run at 8x+8x if your mobo does not have dual 16x... preformance.. eh I dont think its a huge difference, but OC and preformance with 3Dmark and so forth, you dont get the full potential
 
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#4
What model of motherboard do you have? Best is to fill out your system specs in your User CP ...

but yea, if you do crossfire, it will run at 8x+8x if your mobo does not have dual 16x... preformance.. eh I dont think its a huge difference, but OC and preformance with 3Dmark and so forth, you dont get the full potential
I did fill it out i guess i just didnt select to show it to other users :laugh: anyways this is the motherboard that I am talking about

here

Under the specifications it states "1 x PCI Express x16 slots, running at x16 (PCIEX16_1)
1 x PCI Express x16 slots, running at x8 (PCIEX8_1)

For optimum performance, if only one PCI Express graphics card is installed, be sure to install it in the PCIEX16_1 slot. The PCIEX8_1 slot shares bandwidth with the PCIEX16_1 slot. When PCIEX8_1 is populated with a PCI Express graphics card, the PCIEX16_1 slot will operate at up to x8 mode."

So does that mean that if i were to crossfire two cards that it would crossfire at 8x+8x?
 
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#5
That would be correct. Are you wanting to use existing DDR2 or are you going to move to DDR3 which would be a "REAL" AM3 board(supports only AM3 and DDR3). When it comes to crossfire you shouldn't see much difference between a 16x+16x(790FX board) or 8x+8x(790GX and 790X) when crossfiring two cards.
I myself use the Asus Crosshair III, http://www.newegg.com/Product/Product.aspx?Item=N82E16813131392, which is AM3 only and I have been very pleased with it. Very easy to setup, OC in the bios, and comes with alot nice features. Depending if you want to go to DDR3, PP has a nice MSI AM3 board for sale: http://forums.techpowerup.com/showthread.php?t=102418
 
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#6
Yea that is a very nice board...i dont have a lot of money right now since i am in college, so i am weighing my options...i am leaning towards the gigabyte board because its only 109.00 new and from what i have seen ddr3 doesnt make much of a difference in games.
 
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#7
Awesome, I was looking for an AM3 mobo that didn't downscale in dual x16 mode. There is a performance decrease from dual x16 to dual x8, and I consider it significant enough to invest in a 790FX mobo.

http://www.techpowerup.com/reviews/AMD/HD_5870_PCI-Express_Scaling/

I'm looking for alternatives to i7 930 build but at $200 you might as well go i7 looks like.