ATI RV870 and Radeon HD 5870

With new generation of graphics cards comes, naturally, new GPU with RV870 mark. New GPU is made in 40nm manufacturing process that was tested on RV730 and HD 4770 model. "Test model" and transition to new manufacturing process went on smoothly, so before us we have new DirectX 11 compatible GPU supports Shader Model 5.0. Architecture didn’t overdone huge changes and improvements. New GPU actually presents “just” improved GPU from previous generation, but these improvements make this new GPU significantly better one. New GPU has surface area of 334mm2 while "old" RV770 had 263mm2. This small increase is consequence of improved manufacturing process. Transistor count, on the other hand, is significantly increased: more than 100% increase, or exactly 2.15 billion transistors. This much transistors in just one GPU is really impressive figure. Of course, amount of Stream Processors is increased at 1600. They are organized similar to previous models so we have 20 SIMD groups that have 16 Stream cores each. Stream cores consist out of 5 SPs. Of course, every fifth SP is reserved for special functions while the rest 4 are used for base functions. Even without other improvements, this alone would have significant impact on performances. Number of ROP units is doubled which makes this GPU very good material for high resolutions. Because of this ATI was able to present Eyefinity. Texturing units count was also increased, so there are now 80 TU present. Sixth generation Tessellation unit, present in RV870, introduces innovations in area of programmability and new algorithms that should eliminate artifacts during rendering. Beside all this, a lot of improvements are made on Pull model interpolation and OpenGL that got 12bit sub-pixel accuracy (precision).

Improvements didn’t miss even Thread processors which L1 memory bandwidth was significantly enlarged while amount of L2 memory was doubled (128KB per memory controller). Render Back-End units are now twice efficient than it was the case with earlier GPU with implementation of few additional technologies with emphasis on CFAA performances and much better Super-Sample Anti-Aliasing. Since there are a lot of transistors in this new GPU, power consumption was significant problem, but ATI managed to optimize RV870, so HD 5870 will be power efficient. Before all, there is 40nm manufacturing process that lowered power consumption in IDLE, so GPU operates at 240MHz in IDLE (memory frequency is also lowered in IDLE). Thermal protection is realized thanks to present temperature regulator that will be responsible for overall stability of the graphics card. All in all, ATI declared that new HD 5870 will need 27W in IDLE and 188W under Full LOAD. Full Load value is little bit higher than on previous generation GPUs but, IDLE value of only 27W is huge improvement. Multi-GPU systems will also have decreased power consumption but further details were not available at this moment.