Hardware Canucks posted a review on the Sapphire HD 4890 1GB video card
A quote from the article:
>> Sapphire HD 4890 1GB Review
Enter the brand new HD 4890 1GB, a card that builds upon the HD 4870 with increased clock speeds under its belt and supposedly bucket loads of overclocking potential. Essentially, this is exactly what the name suggests: an overclocked HD 4870 with the new designation of RV790. This sticks quite well with what we mentioned about modified versions of existing technologies being used to cement a company's place in the market. Indeed, it seems like ATI has really hit its stride with their current 55nm cores and they are making good use of them once again.
>> Sapphire HD 4890 1GB Review