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TinBane

Crossfire Questions

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I've got a GA-X38-DS4 (a bit old, I know)

and I'm running an AMD 7770.

 

Now, what do I need to use crossfire?

Do I need a special jumper cable to go between the two?

Do I need to do anything special to set it up?

 

Is it best to use two balanced cards, or can you use one slower card and one faster card?

 

And what's the real-world advantage like these days?

I remember when SLI/crossfire came out, the speed up was something like 50 - 80%.

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First up, had a look at your board and it supports crossfire which is good. Some of older boards tend to favour either SLI or crossfire, it's not so much an issue these days.

 

If you want to crossfire your best option is a second 7770. It's possible to crossfire any of the 77xx cards though, so I believe you could use a 7750 if you had one, maybe this also applies to 78xx but not 100% on that. I believe it is then limited to the speed of the slower card, and you'd likely run into performance issues in a mixed config so I wouldn't recommend it.

 

On higher end cards you need a crossfire bridge, similar to SLI bridges, but on simpler cards like the 7770 it's not required. You can simply enable the option for crossfire in the ATI drivers. It should detect the second card and prompt you to enable it once insert a second card and boot up. If not, you'll find it in CCC.

 

These days the scaling is pretty good, but it depends on the application a little. From memory the 7000 series is the most efficient so far, from a quick google of results, it looks like the scaling is around 75%-100% in most situations. Basically your performance/FPS would almost double with a second card.

 

Here is a review from techspot on 7770CF and 7750 CF with some nice charts.

http://www.techspot.com/review/501-amd-rad...fire/page4.html

 

Hope that helps.

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I believe it is then limited to the speed of the slower card

 

and you'd likely run into performance issues in a mixed config so I wouldn't recommend it.

This is no longer the case with crossfire. Each card will run at its own speed independent of the other.

 

Lower specced cards seem to be more prone to microstutter when using crossfire.

 

 

 

 

 

compatible card chart

 

http://sites.amd.com/PublishingImages/Publ...Chart_1618W.jpg

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