Problems with NEC 3540

I have just purchased a NEC 3540 DVD writer and have installed it in place of an older Ricoh CD writer. The settings have been left the same ie the new burner has been set as slave with a NEC 1300A burner as master (on the same cable).
Problem is that the new drive will not burn 4x DVD-r at anything other than 2x.
Software is Nero Express with the latest download.
Any ideas?

It’s not offering speeds of greater than x2 for the media? Could be that the firmware doesn’t like the media you are using, for more expert knowledge either wait around here, or ask again in the NEC forum here:

IF it’s the firmware you might want to try liggy or dee’s firmware rather than the offical one, allows overspeeding and bitsetting.

If the highest burnspeed for DVD is limited to 2x/2.4x, you should check that DMA is activated!!

Thanks for all suggestions. I have since made the newer drive master and the older drive slave, and the problem seems to be solved. The 4x media now burns at 8x!