NEC ND-3520A only 4x?

Just bought a NEC ND-3520A and the firmware is 1.04
Why only show 4X burning speed in Nero??

What type and brand of blank media is in the drive at the time? Nero will only show the available speeds for a specific media. Use a brand and type of media thats on the recommend list for up to 16x burning and the higher speeds will appear as available selections. Like with Verbatim 16x DVD+R and FujiFilm 8x DVD+R. DVD-RW and +RW discs are limited to 4x max only as are some lesser brands of DVD-R and +R.

i got a problem like that but my lower speed for burn is 4x
is a memorex dvdrw but is a nec 3520A oem …

I try different brands of DVD media. They all shown max write speed is 4x in Nero. And also I did try to burn one DVD, it uses 4x to write the DVD.
My old DVD burner is NEC 2510A. It can burn 8x for the same brand of DVD media.

Please post the MIDs of the discs you are testing with.

What version of Nero are you using. Upgrade to latest version to get support for NEC 3520.