Ok , i have an Answer from a Specialist..... DVDROM is controled by program, and seem that firsts Games, like Kameo/NFS/PGR3 and others used First 360 DevKit on which there wasn't Control on DVDROM read speed!!!
New games, like DOA4 or DVD mag, use Last 360 devkit, and Speed is Controled, so no more Noise.
What's not cool, is that playing a game with DVDROM at full speed during some hours will reduce considerably the DVDROM life....
I have experienced recently some lock on game like NFSMW, and it seemed the DVDROM was too hot!!! arghhh