The Cray XT3 processor and I/O boards use socketed components wherever possible. The SeaStar chip, the RAS processor module, the DIMMs, the voltage regulator modules (VRMs), and the Opteron processors are all field replaceable and upgradable. The Cray XT3 system backplane is designed to allow modules to be hot-swapped to replace faulty components without the need for a system shutdown, enhancing system availability. All components have redundant power, including redundant VRMs on all system blades.