i use dvd ripper to rip my dvds, im using samsung 16x dvd-rom
the question is when i start to rip it starts at 2.2x and gradually goes up to about 6/7x. one time it started at 10x and went up to 15x but it has never done it before, why doesnt it do this all the time start at a high speed?

All depends on the source disc (how scratched up it is, coding, ect.)

it does that with every disc, even if its scratch free, any other suggestions?

It depends on CONTENT! 7x is a very realistic ripping rate,for a CSS protected disc.You are getting about all you are going to!