is nothing to do with the mobo, cpu, etc
ur gonna hav to open it up an grease the rods that the laser slides up/down
trust me i had the same proble with my PS2 and my older CD-Rom drive
the problem is that the laser is trying to move down to read the disk but the rods are not greased so the little gears that are attacted to the laser are skipping .
this is only for the older model drives, the new ones use a black rubber band.