Some buyers of the 27-inch Core i7 iMac are receiving unusuable systems, threads on Apple's support forums indicate. In a collection of cases the systems are failing to even turn on properly, at best sounding the Mac startup chime, always failing to display anything more. Apple is reportedly offering replacement iMacs for affected customers, but this may involve a shipping time of two weeks, as Core i7 is an upgrade option not normally sold at retail.
