nec 3500a,3520a,3540a does not read all dvd-r or +r at 16x like it claimed, only on some. The Media Code Sky co.,ltd. 4x and Lead Data 01 are limited to 8x, some are limited to 12x. Switching media strategy has no effect as it still think it's that same media with change in writing speed. I have hundreds of these media, luckily I have an additional dvdrom such as liteon 16p9s which read any dvd-r or +r, rw at 16x. Not that I am impatient but should I need to restore them back to the harddrive it would frustrate me.