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Crossfire with 512+256Mb

Posted: Tue Jul 24, 2007 7:00 am
by brites
Does a CF config with one board with 512 and another with 256 make any improvement over the tradional 256+256? The techs told me that the 512 board could run a little bit slower... does any one know of a bench with this type of setup? TAL :finga:

Re: Crossfire with 512+256Mb

Posted: Tue Jul 24, 2007 7:16 am
by Bwall
In the case of mismatched memory and turning on CrossFire, the Catalyst driver will force you to reboot. This reboot is to disable 256MB of memory on the 512MB card so that the cards will have matched performance, so having a 512MB vs a 256MB will not get any increase in performance.

Hope this helped!

Re: Crossfire with 512+256Mb

Posted: Tue Jul 24, 2007 9:20 am
by brites
But the folks from Sapphire told me that the only thing that could happen was the reduction of speed of the memory on the 512Mb they didn't said the the drivers only recognize 256Mb on each board.... Are they just trying to sell one more card?!?!

Re: Crossfire with 512+256Mb

Posted: Tue Jul 24, 2007 8:10 pm
by Apoptosis
Brites... I asked ATI for you and this was their official response... I dunno what sapphire is telling you but this is direct from the engineers at ATI:
They run as 256MB cards. It runs on the lowest common denominator. This
also applies to pixel pipelines, clocks, etc

Re: Crossfire with 512+256Mb

Posted: Wed Jul 25, 2007 2:06 am
by brites
Thank You for the attention...
I believe the politics in Sapphire is "if they don't cleary ask we won't tell" and here are my Q and their A

Mon, 23 Jul 2007 09:09:02 -0500
Thats ok you can use both together but it might slow down the 512mb slightly

Sun, 22 Jul 2007 14:09:47 -0500
Can I use a X1950Pro 512Mb with an 256Mb in Crossfire mode?

They could have also told me that the entire board would run at the specs of the smaller/slower one;
So I've asked again and this time directly to the reduction of memory:

Tue, 24 Jul 2007 16:34:45 -0500
yes that's correct.

Tue, 24 Jul 2007 08:53:32 -0500
Is it true that in a Croosfire config with 512Mb+256Mb boards the drivers only recognize 256+256, and that they forced this memory availability?

So here it is... when you ask for something be sure to ask like a laywer :finga: