Did 5 systems with week 20's that would do 933 at stock voltage. Had 2 '20's that needed a little bumping, .1 at most. L020409's worked best, at least for me. All were retails and shipped from the Carol Stream, IL Ingram warehouse.
I've got a 550E in the "family machine" that is probably the best P3 O/C'er I've had.