Been on my new 27" imac tonight and now have a banging headache. Never had anything like this on my 21.5" I have noticed I look up more because the 27" is so much taller than the 21.5" I might cut the legs on my desk 8) But if this continues I might have to return it. Would be gutted because the i5 and video card is card. But whats the i5 upgrade like for the 21.5" its not a quad core ? Also the video card isn't a 5750 but a 5670 ? Whats that like compare to the 5750 in the 27" I currently have ?