SAN JOSE, Calif. Archrivals Nvidia Corp. and Advanced Micro Devices will announce their competing next-generation graphics processors Monday (June 16), both claiming their massive multicore chips can deliver a TFlops for graphics and video as well as high-end technical and scientific applications.
But that's about where agreement ends. The two architectures take radically different approaches to multicore, memory, silicon integration, process technology and software.
The new chips come at a time when Intel is preparing its own next-generation architecture dubbed Larrabee, based on many streamlined x86 cores. At an Intel Research event last week (June 11), Intel chief technology officer Justin Rattner said Larrabee represents the start of a long term shift to a new graphics architecture based on ray tracing instead of the traditional graphics rasterization approach, a claim analysts and AMD rejected.
In perhaps the most dramatic difference with past practices, AMD will break with the tradition of delivering a high-end part then evolving lower end devices from it. Instead it will launch a part aimed at the graphics mainstream with a proprietary interconnect that links two chips on a board to deliver top performance.
"We didn't want to come out with one monolithic GPU and then disable parts of it for different markets," said an AMD spokesman prior to a full disclosure of the part in a briefing in San Francisco on June 16.
The strategy makes sense for the financially troubled AMD which also has laid out conservative road maps for its computer processors. The graphics choice reduces costs and risks while maximizing returns for the company which has suffered through multiple loss-making quarters.
The decision to use a two-chip strategy for the high end was made more than two years ago, based on an analysis of yields and scalability. It was not related to AMD's recent financial woes, said Rick Bergman, general manager of AMD's graphics division.
"I predict our competitor will go down the same path for its next GPU once they see this," Bergman said. "They have made their last monolithic GPU."
"On paper the AMD approach looks good," said Jon Peddie, principal of graphics market watcher Jon Peddie Research (Tiburon, Calif.). "If it works, it will be a significant shift in how GPUs are made, but we won't know until later this year" when customers can test the new parts, he said.
AMD says its 4850 device at about 110 W and $199 will deliver about 75 percent of the performance of Nvidia's high-end GTX280 which costs $649 and dissipates 236W. Two of the AMD parts on a board will hit graphics benchmarks about 30 percent higher than the Nvidia device, the AMD spokesman added.
A 4870 version of the product sporting slightly higher performance will cost $299. Both AMD chips are made in a 55nm process, compared to 65nm for the Nvidia chips, and measure about 16x16mm compared to about 24x24mm for the Nvidia part.
The approach gives Nvidia bragging rights for the single most powerful graphics processor, an edge that plays well to the gaming and technical communities who use the parts.
AMD will claim technology leadership in two areas. Its chips will use more than 500 cores, more than double the 240 cores on the new Nvidia parts. They will also use GDDR5 memory interfaces running at about 3.2 Gbits/s or more. Nvidia will use the existing GDDR3 protocol running at up to 1.1 GHz on a 512-bit interface to deliver memory bandwidth up to about 102 Gbytes/s on some versions.
Because memory bandwidth is not increasing as fast as processing resources on the latest Nvidia architecture, some applications may find they are memory bound, said Andy Keane, general manager of GPU computing at Nvidia.
Bergman said the AMD focus on a more mainstream design will enable it to roll out this fall a version for notebook computers that consumes less than 70W. "There's no way this new Nvidia core will be in notebooks this fall," Bergman said.
The Nvidia chips include 1.4 billion transistors running at speeds up to 1.6 GHz. "It's one of the largest chips in mass production and unlike some processors it is not 60 percent cache," said Keane.
Nvidia said its latest chips can handle as many as 30,000 threads at a time, up from about 10,000 threads for its previous generation. It upgraded its latest chips to support double precision floating point math, something AMD already supports.