I once had a dell laptop that after about three years started complaining on power up that I wouldn't be using a genuine dell PSU and should switch to one. I ignored it at first because you could just hit enter and carry on, but after a while I noticed that every time this happened, the cpu would clock at a fixed 800mhz. I ordered a new power brick but the message didn't go away, so I returned the brick and decided to never buy dell again.