Some U.S. resellers were out of stock. A Mac Connection sales representative, for instance, said that the e-tailer's next shipment of 27-in. iMacs was expected Dec. 18. "I don't have any information regarding a reason for the delay," the representative said in a live chat Saturday. Amazon.com reported that a new 27-in. iMac would ship "within 1 to 2 months." ClubMac.com, meanwhile, said it wouldn't have 27-in. models until the end of the month. A sales representative from the California-based e-tailer said only that "Apple is not able to get us our shipments."
Both the dual-core and quad-core iMacs are affected by the flickering screen issue, according to reports filed with Pronych's site. Those models use AMD's ATI Radeon HD 4670 and Radeon HD 4850 graphics cards, respectively.
The 27-in iMacs were introduced in late October, when Apple refreshed its desktop lines. According to Pronych's data, fewer than 10% of the total reports are from users of the less-expensive 21.-5-in. iMacs. The entry-level $1,199 machine uses the NVIDIA GeForce 9400M integrated graphics chipset rather than an ATI graphics card.
If the problem is, in fact, traced back to the ATI graphics cards, it won't be the first time that AMD's hardware has been blamed for iMac troubles. More than two years ago, Apple began investigating screen lockup problems with the then-new iMac line that sported ATI graphics cards. Several weeks later, Apple issued a firmware update that seemed to solve the problem for most users.
This year's new iMacs have also been plagued with performance issues. Within days of their Oct. 20 introduction, users complained about extremely sluggish playback of Flash video. A Nov. 9 update to Mac OS X 10.6.2 targeted the problem, which was resolved for some, but not all, users.
Apple has not responded to multiple e-mails asking for comment on the 27-in. iMac screen issues, including one Friday requesting information about the two-week shipping delay. Apple typically refuses to comment on hardware issues, preferring instead to quietly publish a support document to its site.