Is it possible to replace the hard drive of iMac 27" (late 2012)? I did remember somewhere on Apple official website stated that user can replace RAM of iMac 21" and both RAM and hard drive of iMac 27". But I can't find that page now. Besides, it's strange for iFixit not having teared down iMac 27" late 2012. And I couldn't find the answer on Google. Thanks!