Bigbruin.com posted a review on the Sapphire Vapor-X Radeon HD4890 1GB Graphics Card
A quote from the article:
>> Sapphire Vapor-X Radeon HD4890 1GB Graphics Card Review
Never satisfied with just releasing a typical product, Sapphire now offers a variety of Radeon HD4890 cards, including the factory overclocked Vapor-X Radeon HD4890 1GB unit provided for this review. This card gives the reference design RV790 GPU a slight speed boost from 850MHz to 870MHz, while also giving the GDDR5 memory a bump from 975MHz to 1050MHz.
>> Sapphire Vapor-X Radeon HD4890 1GB Graphics Card Review