How to Limit Drive speed to 3x or 4x?

[766875]

I'm able to use 0=8 to limit the drive speed to 2.0x as I have some discs that are making a grinding noise and failing if I go faster.

What number should I use for 3.0x and 4.0x?

I followed the guide here: viewtopic.php?t=22689

[dcoke22]

I don't know any more than what's posted in the Drive Speed Control page, but what happens if you set it to 12 or 16?

[Jeggo]

The number after the "0" represents the MB/s value. 4x speed is about 16MB/s transfer speed. So "8" is about 2x speed.
As far as I observed values lower than "8" seem to have no effect. Speed remains at 2x.