I know that you have to check what your motherboard supports before purchasing RAM(checking DDR2 or DDR3). Now do you have to check the same for processors? If yes then where can I find out about it, is there a website for this?
You will need to visit the motherboard manufactures website to see which CPU's are supported. Do you know which motherboard you are using? If not you can use programs such as CPUZ and it will provide some of that information to assist you.