AMD is planning to release a cheaper dual-GPU card, the Radeon HD 4850 X2 with 2GB GDDR3 memory. According to FUD Zilla the card will be released a month later than the Radeon HD 4870 X2 2GB for $449, that puts the launch somewhere in mid-September.
Radeon HD 4850 X2 2GB comes with 2GB of GDDR3 memory and we don't think that cooler will look that much different. The 1GB version of Radeon HD 4850 X2 is also possible and ATI will let its partners manufacture such cards.
The first Radeon HD 4850 X2 2GB reference cards are expected in September, while the partner solutions should show up a few weeks after, probably at some point in Q4 2008. After years, ATI partners are starting to feel much better about this red team.