text: i have an ibm aptiva computer with a pentium 150 mhz. what is the max processor i can upgrade that to?   it depends on which motherboard is in it and which model. the fastest that type of board would be upgradable to is 200, 233, or 266 depending the board. 233 was the highest pentium chip made, if it will take cyrix chips, then 266. go to ibm support and seartch for your model, it will probably still have the spec for yours in aptiva support