Optiplex 170l Processor Upgrade

I have 15 Optiplex 170L with the E210882 mother boards which has a MPGA478B chip socket. The workstations currently have Celeron 2.4GHz chips installed. I need to upgrade them to the fastest Pentium 4 processor that I can, in order to run a new program on them and meet the software distributor’s minimum hardware requirements for installation and support services. I can't seem to get a straight answer on which processor I can use and I am also unable to find any info out on my own. Any help would be greatly appreciated.

Thanks in Advance