Crossfire Compatibility

[red99]

In Crossfire: Do brands,model have to match to work? Can 1gb and a 2gb be linked if they have diff. manufacturers? Lastly: Does clock speed have to be identical out of the box if not OCing them?

 

[RejZoR]

Only requirement is that you use the same class and same memory capacity.

So for example 2x HD6870 with 1GB of memory. Or 2x HD6970 etc

Last time i checked different clocks work together as well and brand itself doesn't mean anything.

 

[ComradeSader]

I believe, that if one card has 2GB and one only has 1GB, that only 1GB from both cards will be used. Same deal with clocks. Could be wrong, iunno.

 

[cadaveca]

I believe, that if one card has 2GB and one only has 1GB, that only 1GB from both cards will be used.

Yes

Same deal with clocks.

No, clocks are independant. Same with Shader count.

 

[AlienIsGOD]

as far as i kno Crusader u have it right. mem and clocks will go to lowest common value. brand/company do not make a difference nor does different models within the same class ie. 4850 + 4870 crossfire ( i have seen that here on TPU b4). I personally bought 2 Sapphire as to have minimal issues with Crossfire

 

[t_ski]

If clocks are different, the lowest clock will be utilized. Example is if you have one 6990 and one 6970 for tri-fire, you will use the 6990 clocks. Brands do not need to match as I have done this for years. However, if they run at different clocks (one regular card, one "OC" edition), the lowest will be used.

 

[crazyeyesreaper]

exactly

6850 + 6870 works

5850 + 5870

5830 + 5870

5850 + 5970

5870 + 5970

6950 + 6970

6950 + 6990

6970 + 6990

essentiall family name is all that matters with xfire

x8xx will work together
x9xx will work together so on and so forth

at least when it comes to modern gpus aka not sure on the 2000 or 3000 series but this applies to 4000 5000 and 6000 series cards

 

[2DividedbyZero]

gone are the days where the lowest clock will be utilised.

the memory is critical and the "least" used by a particular card will be used by all:

ex1, a 2gb card xfired with a 1gb card will use 1gb

ex2, a 5850@725/1125 can be used with a 5870@850/1200 WITHOUT effecting clock speed

 

[cadaveca]

If clocks are different, the lowest clock will be utilized. Example is if you have one 6990 and one 6970 for tri-fire, you will use the 6990 clocks. Brands do not need to match as I have done this for years. However, if they run at different clocks (one regular card, one "OC" edition), the lowest will be used.

No. Clocks are not part of it.


Although, i think that they should be.


CCC allows for independant clocking of each card, even.


Only memory size, and use of the same base GPU matters.


You can run 4870 with 4850, 4870 with 4890, 5870 with 5850 and 5830, as well as 5970, and 6950 with 6970 and 6990. NO CLOCKS/SHADER AMOUNTS WILL BE ADJUSTED.

 

[Zubasa]

No. Clocks are not part of it.


Although, i think that they should be.


CCC allows for independant clocking of each card, even.


Only memory size, and use of the same base GPU matters.


You can run 4870 with 4850, 4870 with 4890, 5870 with 5850 and 5830, as well as 5970, and 6950 with 6970 and 6990. NO CLOCKS/SHADER AMOUNTS WILL BE ADJUSTED.

This.
Only difference you will see is the faster card with have a slightly less load %.
For example, a stock 5870 CF with a OCed 5870, the OCed card will be loading at 95% while the stock card will be at 99%.

 

[t_ski]

gone are the days where the lowest clock will be utilised.

the memory is critical and the "least" used by a particular card will be used by all:

ex1, a 2gb card xfired with a 1gb card will use 1gb

ex2, a 5850@725/1125 can be used with a 5870@850/1200 WITHOUT effecting clock speed

No. Clocks are not part of it.


Although, i think that they should be.


CCC allows for independant clocking of each card, even.


Only memory size, and use of the same base GPU matters.


You can run 4870 with 4850, 4870 with 4890, 5870 with 5850 and 5830, as well as 5970, and 6950 with 6970 and 6990. NO CLOCKS/SHADER AMOUNTS WILL BE ADJUSTED.

This.
Only difference you will see is the faster card with have a slightly less load %.
For example, a stock 5870 CF with a OCed 5870, the OCed card will be loading at 95% while the stock card will be at 99%.

Not according to this article:

http://www.hardocp.com/article/2011/04/11/amd_radeon_69906970_crossfirex_trifire_review/

Therefore, what happens is the triple-GPU setup will only run as fast as the slowest system. Meaning that though the Radeon HD 6970 video card can run at 880MHz/5.5GHz, it will synchronize with the slower 830MHz/5GHz clock speeds of the Radeon HD 6990. You still have all the goodies, 2GB of RAM, same shader count, but just slightly reduced clock speeds on that video card. Still, we have a lot of processing power.

 

[cadaveca]

Not my fault Brent failed.


What can I say? He made a mistake? Because I know, for a fact, from doing it myself, you can adjust card clocks separately with that combo. I really make an effort of saying nothing unless I've tried it myself.

 

[t_ski]

I never said you could not adjust the clocks separately. It just means that if you throw mixed carfs in there, that they should default to the lower speed. You're free to OC from there all you want.

 

[cadaveca]

I never said you could not adjust the clocks separately. It just means that if you throw mixed carfs in there, that they should default to the lower speed. You're free to OC from there all you want.

Never seen it happen, myself. I can explain why it looked that way to brent, but he's wrong. Install the 6970 first, as I did, and something far different happens. I think maybe he ran two 6990's on that OS before the triple setup, although it could be possible that my differnt earlier config is truly what's the cause.

And he did say syncronize, not actually drop clocks, which may kinda cover him there, as Zubasa states above.