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Couple quick questions about Crossfire

O

Ovreel

Limp Gawd
Joined
Apr 23, 2008
Messages
292
If I crossfire a card with 1gb memory with another that has 512mb memory, will I get the full benefit from both cards? (Sorry if this is a dumb question, just thought I'd check since I know if you xfire a XX70 with a XX50, the XX70 gets brought down to the XX50 clocks.)

Also, does it matter which card goes in the main PCI-E slot? Will it matter if the 512mb card or 1gb card is in the main slot? My 512mb card has an HDMI slot which I use, but the 1gb card does not, so I've left the 512mb card in the main slot.
 
No it doesn't matter which pci-e slot the vid cards are in.

If u had a 1gb and a 512mb you'll only get the benefit of the lesser card. (512Mb)
 
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Also - if you Crossfire two cards (your example of an xx50 and xx70), it does not cap the one out at the top speeds of the other - the clocks are completely independent of each other.

Apoppin, a member here on the [H], has done some testing on this. A "Frankenfire" combo, as he puts it, will not drop to the lowest speed between the two cards, instead they will perform at a rate in-between that of a (for example) xx70/xx70 and xx70/xx50 setup.

I can also personally attest to this, as I used to have a 5770 CF'ed with a 5750 some time ago, and it consistently benched higher than a 5750x2.

He made a rather in depth article on it some time ago. Worth checking out.

http://alienbabeltech.com/main/crossfire-x-explored



 
On the RAM front, no, you'll only have an effective total of 512MB. While clock speeds/base performance are unaffected by mismatched Crossfire, the only one area you are limited is by the amount of RAM on the card with less memory. Both cards are going to have the same information (essentially) in the memory, so, it's not an additive calculation.

The pair would function as if they both had 512MB each, for a total effective memory of 512MB. The extra 512MB on the second card would go unused, because it cannot mirror that info with the other card.
 
Damn. Wonder if it would be worth it to upgrade the 512mb card to a 1gb version.
 
RoboTrip said:
Also - if you Crossfire two cards (your example of an xx50 and xx70), it does not cap the one out at the top speeds of the other - the clocks are completely independent of each other.

Apoppin, a member here on the [H], has done some testing on this. A "Frankenfire" combo, as he puts it, will not drop to the lowest speed between the two cards, instead they will perform at a rate in-between that of a (for example) xx70/xx70 and xx70/xx50 setup.

I can also personally attest to this, as I used to have a 5770 CF'ed with a 5750 some time ago, and it consistently benched higher than a 5750x2.

He made a rather in depth article on it some time ago. Worth checking out.

http://alienbabeltech.com/main/crossfire-x-explored
Click to expand...

I have to ask since you have first hand experience outside of just benchmarks. Was there any strange performance? Microstutter? Did it really perform as well as two similar cards?
 
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