Ok the problem seems to be very common - NEC 1300A based writers somehow only burn some media which is 4x at only 2x, regardless of the setting of speed. I tried all kinds of firmware and nothing helped. I noticed, however, a very ridiculous phenomenon! If in Nero, i select “determine maximum speed,” then it does write at full 4x after speed check! And if I dont enable it, its doing the job twice the time (the 2x problem).
Any ideas on other solutions or reasons of why such “solution” works?