Proving AMD's intention to continue the tussle with nVidia to produce yet faster single-chip graphics cards, specs and some photos of the ATI Radeon 4890 have leaked out, via the Chinese Pc Online. The card looks to be a step up from the Radeon HD 4870, in a similar vein to nVidia's GeForce GTX 295.
From the outside the Radeon 4890 doesn't looks particularly different from any other 4800-series graphics card, but on the inside there are a few notable changes. Clock speeds are set 850MHz and 3.9GHz for the core and memory - on the leaked chip at least. The 4870 was limited to a 790MHz core clock at most, via ATI's Overdrive overclocking utility, whereas the leaked 4890 has a 1GHz limit, indicating there's headroom for improvement on retail cards.
The improvements are speculated to come from a die shrink - from the currently used 55nm to a 40nm manufacturing process - which would explain why AMD was able to give the chips clock speeds such a notable improvement. A die shrink would also result in improved yields for AMD, not to mention a lower cost-per-chip - hopefully some of that saving will be passed onto us consumers.
A couple of retailers overseas have the Radeon HD 4890 up for pre-order in the £250 region. Assuming the leaked clock speed information is correct, the 4890 should prove a compelling buy once it becomes official.