Apple’s (AAPL) manufacturing partners have reportedly begun mass shipping new iMac All-in-One desktop models as well as new 13-inch MacBook Pro notebooks equipped with Retina displays into distribution channels. Citing unnamed sources within Apple’s supply chain, Digitimes on Monday reported that the new computers will likely become available either in September or October to target back-to-school demand. The news comes just after a recent report claiming Apple is preparing to launch a new iMac lineup imminently. Digitimes claims that display panel supply constraints will prevent Apple from launching a new high-end iMac in the coming weeks, but the company still plans to introduce new entry-level and mid-range models.