It's presently on UDMA Mode 2, which I assume is the device default (fastest).
I have no issues with transfer rates; I occasionally use it to make backups, and it will happily run to 8, 10, 12x and beyond when ripping a disc.
I should note that the drive isn't even trying to burn past 4x. It's not running out of buffer, and there are no bottlenecks whatsoever, such as getting information off the source drive.
It's as if the burner is overriding my selection for some reason. I know some drives (Liteon?) will automatically use a lower speed when using suspect media in the interest of burn quality, but I didn't think the Benq did this other than slowing down on the fly. Still, it doesn't matter what media I use-- Cheap fakes, or top shelf Yuden000 T02, it will always start and finish at exactly 4x CLV regardless of what speed is chosen, or what options are set in QSuite.
I'm puzzled! I think it's time to rip the drive apart and do a thorough cleaanig.