1653 with winx64: constant read speed (cav)

i updated my system to a new Athlon64, and i am running Windows x64 edition, i used as DVD writer the one i had on the old computer which is a Liteon 1633@1653, which worked great on the old system.

on this system it is behaving a bit strange when reading, here is an example (test was aborted by me, i don’t want risking damaging the drive):
this is nero cd speed making a speed test on a pressed CD-rom, but same results occur with cd speed for DVD’s i burn, it doesn’t respect the speed i select (check the other thread i opened sometime ago: http://club.cdfreaks.com/showthread.php?t=175590)

anybody encountered this problem? having a CD rom reading at such high speed is a bit dangerous, or what?
i don’t have the oppurtunity to try with win32, as the x64 windows is the only i have for now.