Gamepyre posted a review on the Diamond Viper HD 3850 PCIE 512MB Crossfire

The HD3850 is an interesting card in the grand scheme of ATI's lineup
and Diamond's 512MB version of the card is also interesting in that the card
lies right in the middle of the 3850 to HD3870 price range. The price for this
card online is $199.99, on Diamond's website and $179.99 at the lowest price available, which is $10 more than the 256MB version of this card. Compared to its lower memory sibling, the 256MB HD3850, a 512MB 3850 provides more performance for just a little more money. The 3850 from Diamond comes default clocked, meaning that the performance increase only comes from the extra memory on the card.

Diamond Viper HD 3850 PCIE 512MB Crossfire Review