It is reported that Nvidia may launch its upcoming single GPU core graphics card GTX 870 and GTX 880 would be launched by Q4 2014, specifically somewhere between October and November. These cards will be based on Nvidia’s GM204 core which is based on 28nm fabrication process.
It is speculated that Nvidia GM204 chip will use 3,200 CUDA cores, 200 TMUs, 32 ROPs and a 256-bit wide GDDR5 memory interface.
Initially, it was supposed to be 20nm, but neither AMD Radeon or Nvidia would wait for a newer fab process to be manufactured by TSMC. However, there’s also a chance that GM204 would not be used until TSMC can fabricate 20nm processors and then become a successor to the existing GK104 chip.
Edit: It should be noted that a new shipping manifest points out GM204 card with 8GB GDDR5, and other GM204 with 256bit interface:
A post was made in XtremeSystems with claims that GTX 880 will be using 512 bit memory bus with 384 TUMUs. According to a shipping manifest, A GM204 GPU sports a 256Bit bus with 128M interface which is shipped via ‘Hyderabad Air Cargo’.
Interestingly, another description of the shipping manifest points out another GM204 card with 8GB GDDR5 viz. shipped from China to Bangalore Earlier, the reports of GTX 800 series GPUs did surface before via the shipping manifest details.
Although this may not give any concrete evidence, but most likely the GM204 card with 256Bit bus may most likely be GTX 870 graphic card, whereas the 8GB GDDR5 memory could be the GTX 880 desktop graphic card. Knowing that the 256bit version is valued at Rs. 34,034/- (US$ 566.24) and 8GB variant valued at Rs. 52,080/- (US$ 866.48), this could be a safe assumption.
Though its not confirmed whether TSMC is fabricating GM204 chips with 20nm or 28nm process, WCCFTech points out that the Maxwell GM204 architecture will only sport 256Bit bus.