Before buying first of all decide what your use is. Make sure about what type of user you are. Are you a programmer? Go for dos boards and linux as well as ubuntu dos. Processing is main so it should be more like core i5 5th generation and above coupled with 8GB DDR3 RAM and a 500GB harddisk is enough. But if you are a gamer then kindly lose some more and more and more. Just look for serials that graphics cards have. Go for Nvidia with i5 7th gen and above for best gaming.