If you close 5 out of 12 then that would definitely bring your available revolving credit down and that can definitely bring your score down. If you have some crappy cards with a $300 or $500 credit limit then you can go ahead and shut 'em down but be careful with the ones with a Credit Limit of a few thousand. For example, I have an Amex with a $30K limit. I know if I close that card then that will kill my Credit Score. However, I had a couple of stupid Capital One with a limit of $300 which I closed in a blink. Especially if you are paying an annual fee on those then just close them out in a blink.