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Video Card(s) x16 vs x8/x8

Last response: in Graphics & Displays
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July 7, 2009 11:18:25 PM

The motherboard I am running has Crossfire capabilities, and since this is my first build I figured one video card would be enough, but I'm getting greedy and want to experiment but have some questions I figured some of you would know.

I am running a Radeon HD 4850 512MB at x16 on PCI Express 2.0
My motherboard is a Gigabyte MA-GA790XT-UD4P, with two PCI express slots (one at x16 and the other at x8, but according to the manual it can only crossfire at x8).

My question is:
Would I get optimal system performance from running TWO of those video cards in crossfire? The catch is my motherboard only supports x8/x8 in crossfire rather than one card at x16. Is there a way to bypass that, such as a certain type of overclocking? If not, would it still be a system boost running 2 cards at x8/x8 opposed to one at x16?
Thanks for any info.

More about : video card x16

July 7, 2009 11:27:39 PM

no overclocking can give you extra pcie lanes. rather, you would need a better chipset
but considering that you have pcie 2.0, you should be fine and would get the full benefit of x-fire
July 7, 2009 11:29:59 PM

daft said:
no overclocking can give you extra pcie lanes. rather, you would need a better chipset
but considering that you have pcie 2.0, you should be fine and would get the full benefit of x-fire


So I'd be benefited from running two x8 over one x16? I should notice a system boost?
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July 8, 2009 12:16:25 AM

bdonedge said:
So I'd be benefited from running two x8 over one x16? I should notice a system boost?

It depends on your monitor resolution, CPU, and the games you intend to play. If your going to run some relatively modern titles, then I can say with some certainty that you will get a boost in performance.
July 8, 2009 12:42:33 AM

g3force said:
It depends on your monitor resolution, CPU, and the games you intend to play. If your going to run some relatively modern titles, then I can say with some certainty that you will get a boost in performance.


I'm running a 19" widescreen with a maximum of 1440x900, and a Phenom II x3 720. If I will get a noticble boost, I think I'm going to go ahead and buy another one of my video cards, because they sell for 100 bucks. That's a steal for the hardware speed. You're thinking it's a go, then?

Edit: I play modern FPS games, occasional MMO's.
July 8, 2009 4:54:06 AM

I'd say it wouldn't really benefit you unless you have like 1920x1000 and running 8xAA and 16xanisotropic filtering. You also have to take CPU and RAM speed into account with FPS. I got a 10 fps boost in CS:source when i went from ddr2 800 ram to ddr2 1066
a c 106 U Graphics card
a b V Motherboard
July 8, 2009 2:59:20 PM

Check the charts and read some crossfire reviews to get an idea of the difference. With most games you'll get at least around a 50% increase. In games that scale well it can be much closer to 100% assuming your CPU can keep up. Even if you disable crossfire for a particular troublesome game and run it on one card, the performance penalty for using an 8x PCI-E 2.0 over a 16x for a 4850 is only like 1-2%.

Just get another 4850, CF it, and be happy :D .
July 8, 2009 9:29:18 PM

megamanx00 said:
Check the charts and read some crossfire reviews to get an idea of the difference. With most games you'll get at least around a 50% increase. In games that scale well it can be much closer to 100% assuming your CPU can keep up. Even if you disable crossfire for a particular troublesome game and run it on one card, the performance penalty for using an 8x PCI-E 2.0 over a 16x for a 4850 is only like 1-2%.

Just get another 4850, CF it, and be happy :D .


The issue i'm having is I've checked plenty of charts, but I can't seem to find anything comparing one Video Card at x16 to crossfiring at both the x8/x8 and x16/x16. I already have the board, not gonna go out and cop another one just for the sake of upping the capabilities, but the problem is all of the charts and reviews and I've only seen things comparing x8/x8 to x16/x16, both are great scores but if I don't notice a difference then I'm not going to waste the money. You are claiming that I am, but even with bottlenecked resources at x8, I still should see a signifcant increase?
July 8, 2009 10:07:53 PM

bdonedge said:
The issue i'm having is I've checked plenty of charts, but I can't seem to find anything comparing one Video Card at x16 to crossfiring at both the x8/x8 and x16/x16. I already have the board, not gonna go out and cop another one just for the sake of upping the capabilities, but the problem is all of the charts and reviews and I've only seen things comparing x8/x8 to x16/x16, both are great scores but if I don't notice a difference then I'm not going to waste the money. You are claiming that I am, but even with bottlenecked resources at x8, I still should see a signifcant increase?

http://www.tomshardware.com/reviews/crossfire-pci-express,2095.html
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