Nero CD Speed Quality test

For the quality test does it matter if i choose the read speed at 8x and maximum? will the results defer?

The result will differ.
8x is the standard.

As far as I know, for the BenQ 1620, 8X and maximum are exactly the same - no difference at all.

That said, you can still select a faster speed to scan at than “maximum” - both 12X and 16X are faster.

What is the max certified speed of the media? if you scan 8X media then the default, not manual override, is max = 8X? so I guess.

It’s nothing about the media. All media are treated equally in CDSpeed, as far as I know.
Selecting max will scan a disc at 8x.

If you want to save some time, try 12x or 16x scan on your own judgement. Personally, I think 12x scan is reliable.

Make sure you have V3.70. Some of the older versions would only SCAN at 8X. The newer version can SCAN at 12X and 16X also.