As if we didn't already have enough graphics cards on the market, AMD is apparently set to launch yet another one, if leaked slides somehow acquired (probably best not to ask) by VR Zone can be believed. The 4830, as it is named, seems set to take on nVidia's 9800GTX in the upper-mid-range market.
Marking the difference in target market from the higher-end 4800-series cards, the Radeon HD 4830 has 640 stream processors, down from the HD 4870 and HD 4850's 800. Memory is limited to GDDR3 as opposed to GDDR5 and uses a 256-bit as opposed to a 512-bit interface.
Clock speeds are a mystery, but it seems likely given the reduced number of stream processors that they'll be fairly in line with the rest of the 4800-series. Was I being cynically minded I might suggest that the 4830 is likely to be made from RV770 chips not quite making the grade as a fully fledged 4800 - although only AMD can know that for sure.
According to the leaked information the AMD ATI Radeon HD 4830 is set to launch on the 21st of October in the $150 (~£83).