Customers hoping to order a new iMac will be faced with shipping delays for any model, with Apple now estimating a two to three week wait for the 21.5in model, and up to a month before new orders of the 27in iMac will be dispatched.

Earlier this month, we reported that Apple appears to be suffering from a shortage of 27in iMacs, with dispatch estimates across the globe of 3-4 weeks. Now, it looks like Apple is also running low on its 21.5in models, with online Apple Stores in the UK and US showing shipping delays of 2-3 weeks.

The shortage of 27in iMacs is believed to been caused by mass production issues that are preventing Apple from being able to make the computer's large display panels fast enough.

However, until now, the production of the 21.5in iMac was thought to be strong, with reports suggesting that around 300,000 to 400,000 units of the smaller model are being shipped each month. Since its launch late last year, estimates for Apple's 21.5in iMac models had remained at 7-10 days.

It's unclear whether Apple's lengthened dispatch estimates are the result of a manufacturing issue, or perhaps high demand for the 21.5in iMac. Apple introduced the Fusion Drive upgrade option for the entry-level 21.5in iMac earlier this month, which could have contributed in a spike in demand for the smaller model.

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