the difference is that 256-bit mem controller can give 2x the bandwidth compared to the 128-bit counterpart when both of them are working on the same clockspeed..
btw from the legitreviews webby when AA and AF is turned on, the 4670 can even beat 9600gt

Legitreview's 4670 review

Pretty sure the 4670 would win. The 4670 beats the 3850 512MB, so 256 would most likely get slaughtered.

Wow ATI seems to be in heads up..

how far do u guys recon the price of the 4670 will drop...?? how much longer do i have to wait..

and can we say tat 4670 is a par with 3850...?

GTG

honestly i prefer HIS ICEQ version better (no offense Gainward fans), but if Gainward could offer the same thing for a much cheaper price, then why not?

ICEQ HD4670:

not light. but UV Effect

4830 strike on the middle.
4830 performance is superior than 4670, and it is 256 bits memory bandwidth, 640 shader processor, based of RV770 LE chip, lower ppwer consumption overall as compared to 4850 cards.
4670 is of 128 bits memory bandwidth, 320 shader processors, based on RV730 chip.
They are of different class of graphic card!!

4830 card is for the performance mainstream, 4670 is only for mainstream.
4830 series of graphic cards are expected to debute later on this month (end of october, 2008)