I like s0lar had a similar problem though I managed to beat the 4x for all media and at least get 8x going but burning at 12x or 16x results in long lead in times and writing at 4x even if its real 16x media not just overspeeding Prodisc or TY.

I'm in the process of RMA'ing my drive but I gave your suggestion a go with regards bittsetting and it didn’t work for me and by the way I'm on an Intel 875P chipset so on this reassuringly expensive motherboard it should be working just fine : (

I believe the drive is defective somehow and hopefully the replacement will solve the problems (by the way I contacted BenQ about my problems and they said none of that behaviour should be happening at all and to return the drive).