My benq 1640 don't like BSOB firmware!

the fact is that when i put bsob firmware my writer won’t read some dvds,he burn dvds much slower than it’s normal(25 mins with 4x speed).
with other firmwares i don’t have any problems.
why?

have you checked if the drive is in DMA mode after the firmware flash?

it was in pio mode,ha.

thanks!!!