A Question about ATI CrossfireX

Hello guys.

I have a Sapphire ATI Radeon HD 4870 512Mb card in my system right now.
http://www.overclockers.co.uk/showpr...=56&subcat=939

I have room to add another card in there in CrossfireX mode.

I was wondering a few things...

1. If I was to add a 1024Mb card, would I end up with 1536mb, or would It only use 1024mb?
2. If the 1st question equals only using 1024 then could I use the "toxic version" with the standard and benefit from its better speeds?

Toxic version here: http://www.overclockers.co.uk/showpr...=56&subcat=939

For some reason its £30 cheaper, I think its because they've got a lot more in stock or something, no idea!

Thanks in advance guys.

1. I think it would just be 1024mb
2. Both cards must have the same clocks, so you could try to overclock the slower card to match the faster one, or the faster one would drop speed to match.

4870 are like super bargains now....

1) in crossfire mode data in both cards' RAM is mirrored. So the smallest common denominal will be utilized.
2) clocks are irrelevant for crossfire to work.