Nodes 600 to 603 are SLES SP2, nodes 604 to 607, 700, 701 and 800 are SLES SP3. To ensure that users submitting MPI jobs reference consistant libraries we've added SP2 and SP3 as text tags to the nodes file. You can add these to your requirements list in your job submission: #PBS -l nodes=1:ppn=1:SP2