Cray has partnered with AMD to offer AMD Opteron™ processors on Cray XT4™ and Cray XT3™ supercomputers as well as Cray's new XT5™ family of supercomputers. The industry leading AMD Opteron microprocessor offers a number of advantages for superior performance and scalability.

The AMD processor's on-chip, highly associative data cache supports aggressive out-of-order execution and can issue up to nine instructions simultaneously. The integrated memory controller eliminates the need for a separate Northbridge memory controller chip, providing an extremely low latency path to local memory — less than 60 nanoseconds. This is a significant performance advantage, particularly for algorithms that require irregular memory access. The 128-bit wide memory controller provides 10.6 to 12.8 GB/s local memory bandwidth per AMD Opteron, or more than one byte per FLOP. This balance brings a performance advantage to algorithms that stress local memory bandwidth.

HyperTransport™ technology enables a 6.4 GB/s direct connection between the processor and the interconnect, removing the PCI bottleneck inherent in most interconnects.

AMD's Torrenza Initiative

AMD's Torrenza open innovation platform allows Cray and other partners with acceleration technology to increase system performance, scalability, and flexibility. Capitalizing on the Direct Connect Architecture and the AMD64 platform, the Torrenza initiative enables innovation within a common ecosystem. Its open socket specification allows Cray customers to use AMD Opteron processors, Cray custom multithreaded processors or FPGAs in the same high-performance fabric.