The increased ship-by estimates come less than a week after Apple's UK online store saw an identical slip, with previous delivery dates of 7 to 10 business days falling to 2 to 3 weeks.
A report earlier on Friday cited a Chinese news source as saying Taiwanese component suppliers improved production rates of the new iMacs, with mass production of the desktops supposedly ramped up in December of 2012. In Apple's recent quarterly earnings conference call for the first fiscal quarter of 2013, CEO Tim Cook said iMac supply would increase significantly over the coming weeks, but warned that "very strong" demand may keep the company from reaching an optimal supply balance until the second quarter.
Supply issues were first seen in early January, when AppleInsider was first to report that Apple's reseller channel was seeing stockouts of the 21.5-inch iMac model.
Thought to be a culprit in the slow iMac production rates is the complex screen lamination process Apple is using to reduce the desktop's overall thickness. Suppliers were reportedly having problems implementing the technology, leading to low yields. Production was thought to be especially poor with the 27-inch model, which as of this writing is sitting at a ship time of 3 to 4 weeks.
According to Apple, iMac supply constraints were to blame for a 17 percent drop in Mac sales for the last quarter. For the three-month period ending in December, Apple sold 4.1 million Mac desktops and laptops, down from 4.9 million units from the previous quarter and 5.2 million units from a year ago.