Help! Won't burn faster than 1.6x when burning with multiple burners!

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.

Any ideas?

hmmm…used to show 18x speed as option, but now it only shows 2.4x as the max. Perhaps that is the problem.