Did you overclock your CPU? Overclocking = void warranty. Intel can tell if you've overclocked it. If you're returning it to the retailer, I hope they fall for it. If what I just said makes you feel weary, go to CompUSA and buy a brand new one (a better one hehe) then swap 'em. I think their return policy of a 15% restocking applies to opened software and printers with cartriges installed. I don't know where you're from, but here in California most of the pple who work there are high school students and they don't know sh** about computers.
I wish you the best of luck.