A mention of mysterious ATI Radeon HD 5900 family of graphics cards in beta drivers causes more questions than answers regarding the roadmap of ATI, graphics business unit of Advanced Micro Devices.
ATI seems to be working on an enhanced version of its ATI Radeon HD 5000-series graphics cards aimed at high-end market. While it is hardly surprising that ATI would prefer to sustain performance leadership after its arch-rival Nvidia Corp. releases its Fermi-G300 high-end offering, it is not clear whether the company plans to overclock its code-named Cypress chip, develop a completely new ASIC [application specific integrated circuit] with increased clock-speed, introduce a graphics processing unit (GPU) with increased amount of stream processors, or completely change its long-established naming scheme and just put two existing chips onto the same board.
The Mysterious ASIC “689x”
The latest OpenCL beta drivers from ATI-AMD apparently support ATI Radeon HD 5900-series graphics solutions, according to visitor of Beyond3D forums, who claims that he has obtained the drivers. The new Radeon 5900-series has device identifications (dev ids) “689C” and “689D”, whereas the existing Radeon 5800-series of chips (also known as Cypress) carry “6888” and “6889” dev ids.
Traditionally, identifications for different graphics cards based on the same chip are similar: ATI Radeon HD 4800 graphics cards based on the RV770 chip have 9440, 9441 (Radeon HD 4870 X2), 9442, 944C, 9443 (Radeon HD 4850 X2) device ids, whereas ATI Radeon HD 4800 boards powered by the RV790 chip carry 9460 and 9462 identifications. As it can be seen, the combination of the first three symbols in dev id describes the actual ASIC, whereas the fourth symbol describes the actual implementation (including speed-bin and/or the number of ASICs onboard).
Considering that ATI Radeon HD 5900 has “689x” identification, whereas the Radeon HD 5800 carries “688x” id, the actual ASICs should be different, unless AMD changes the identification scheme that has been used for many years.
Several weeks ago rumours emerged that ATI has Radeon HD 5890 graphics card in the works. In fact, even one of AMD’s official documents mentioned the HD 5890 model, but a representative for the company said that was a typographical error. In any case, potential HD 5890 model would be a speed-bin of the Cypress/RV870/HD 5870 solution.
ATI has never used different series names for products that are generally similar, e.g., have equal amount of execution units and feature set, but run at different clock-speeds (at least, in case of high-performance solutions), which is why the Radeon HD 4890 (RV790) did not carry HD 4970 model number and the Radeon X850 (R480) was not called X900, even though their device ids were completely dissimilar due to different ASICs.
Based on device ids, the Radeon HD 5900 product series will feature a brand new ASIC, hence, unless AMD decided to make drastic changes to dev id scheme, the HD 5900 family does not feature two Cypress/RV870/HD 5870 GPUs.
The Fifth ASIC of the Evergreen?
According to ATI, Evergreen family of chips features four ASICs: Cypress (5870, 5850), Juniper (5770 and 5750), Redwood and Cedar. In fact, four chips is already a lot since traditionally both ATI and Nvidia Corp. release three chips in the initial lineup, even though later on they could add more processors to the family (e.g., RV740 was released more than half a year after RV870, RV830 and RV810 were introduced, whereas the R500 family eventually consisted of five ASICs). But is it possible that the Evergreen series of DirectX 11-compatible GPUs will consist of five ASICs?
It is hardly logical for ATI to develop five chips, considering its “sweet spot” strategy that eliminates ultra high-end “megachip” with a dual-chip solution. Still, since the Evergreen is likely to remain on the market for about a year, it is completely possible that eventually AMD launches its fifth ASIC that will be sold as Radeon HD 5900-series. Actually, apart from dual-chip Hemlock solution (HD 5870 X2), ATI may have another ace up in its sleeves: a chip with something like 24 SIMDs (1920 stream processors) or with 20 SIMDs (1600 stream processors), but with 1GHz+ target clock-speed.