La 5830 es mas lenta que la 4890 por eso es que no ha subido su puntaje, aqui el review:
http://www.xbitlabs.com/articles/video/display/xfx-radeon-hd5830_15.html#sect1"So, the Radeon HD 5830 can be up to 23% slower than the Radeon HD 4890 and up to 49% slower than the GeForce GTX 275 at a resolution of 1280x1024."
"The XFX Radeon HD 5830, and any other versions of that Radeon working at the reference GPU and memory frequencies, is far from brilliant at a resolution of 1680x1050, either. It is only better than the outdated GeForce GTX 275 in two tests while having a comparable retail price. That’s not what we had expected from an inexpensive RV870-based solution."
"So, we can see that the Radeon HD 5830 is inferior to the GeForce GTX 275 and comparable to the GeForce GTX 260 which can be bought for much less than $200."
Lo bueno es que ofrece dx11 y eyefinity cosas que las 4890 no tiene, ademas de un menor consumo de energia...