Apparently, launch of AMD's Radeon HD 8800 series is close enough for some sources to come up with specifications. The HD 8800 series, according to one source, is based on a new silicon codenamed "Oland," which is built on the 28 nm process, packing 3.4 billion transistors with around 270 mm² die-area. According to the source, the two HD 8800 series models, the HD 8870 "Oland XT" will up performance per Watt and cost-performance ratios over current HD 7800 series, while maintaining current process technologies.
The Radeon HD 8870, according to numbers provided by the source, could offer performance comparable to today's high-end GPUs. The HD 8870 is clocked at 1050 MHz with 1100 MHz PowerTune Boost frequency; while the HD 8850 is clocked at 925 MHz with 975 MHz boost frequency. The memory of both SKUs is clocked at 6.00 GHz, yielding 192 GB/s memory bandwidth. The chips hence have 256-bit wide memory interfaces.
Key details such as stream processor, TMU, and ROP counts are excluded, though the source mentions that the HD 8870 provides up to 75% higher single-precision floating point and up to 60% higher double-precision floating point performance over its prdecessor, the HD 7870. The texture fill-rate is up by 65%. The Radeon HD 8850 offers similar increases over its predecessor, the HD 7850. Find them tabled above.