Is there a way to specify the ppn ( or equivalent ) in SGE ? i don't want to use all cpus in one node so i will be able to have more memory per core. ( In PBS you would do -l nodes=16:ppn=2 for exemple)
You need to set up a parallel environment in order for a job to run in parallel on multiple nodes. Read man sge_pe for details. When running in a parallel environment, the memory request is interpreted as being per-slot.