Haven't figured it out yet. I do know that burning single dvd's using nero express is fine. I'm using version 7.5.9.oa with 4 lg dvd burners. 2 are gsa-h42n, one is gsa-4163b other is external 2164.
My write time when burning individually is about 3:30, but once I try to burn using multiple recorders in nero burning rom, it ends up taking 15 min! it says it burned at 18x when it finishes, but I checked the display actual speed and it shows only about 1.5x write speed.