Techpowerup found photos of Gigabyte's Radeon HD 4890 graphics card on Asian tech site XFastest.
The Gigabyte Radeon HD 4890 1 GB (model: GV-R489-1GH-B) is based on AMD's reference design, which has been pictured earlier, and whose early 3DMark performance figures have began surfacing. The card, features 1 GB of GDDR5 memory, which now seems to be the standard amount of memory on the reference design card. The unboxed card has been pictured from a good angle, which gives us a better indication of its length. It is longer than the HD 4870.
TPU also points out there are pictures of a disassembled Radeon HD 4890 at DailyTech, and that it appears that the RV790 has a slighly larger die than the RV770. Nothing is official yet, but word is going around that the RV790 is not simply an overclocked Radeon HD 4870. The launch is slated for the second week of April.