Chris, Columbia has 6mb cache. Are we cache bound? Would we take a huge hit with a 3mb cache? Have you tried spanning multiple clusters (>512 procs) using InfiniBand? A. -- Dr Alistair Adcroft http://www.mit.edu/~adcroft MIT Climate Modeling Initiative tel: (617) 253-5938 EAPS 54-1624, 77 Massachusetts Ave, Cambridge, MA, USA