The new Power Mac, which Apple announced at last month's Macworld Expo in San Francisco, helps Apple narrow the megahertz gap between its computers and those that use Intel processors.
Cupertino, Calif.-based Apple had said the new Power Mac would ship in February.
Despite Monday's announcement, supplies of the $3,499 systems are expected to be extremely tight. Apple executives have said demand is expected to be higher than supply throughout this quarter for the high-end machine, which also comes with Apple's new iTunes and iDVD software.
The start of shipments comes on the eve of this week's Macworld Expo Tokyo, where Steve Jobs is expected to announce new iMacs, most likely including rewritable CD drives.
Apple is counting on the new models to help boost sagging sales. The company lost $247 million in its most recent quarter as it slashed Mac shipments in an effort to whittle down 11 weeks' worth of inventory that had piled up on the shelves of retailers and distributors.
The effort succeeded in halving the inventory to a more normal five and a half weeks, Apple said last month. However, sales appear to have not picked up much in January. According to new figures from PC Data, Apple's sales in U.S. retail stores were down 60 percent last month from the same period a year earlier. Apple's overall sales, including mail order, were down 40 percent in January, year over year.
Salomon Smith Barney analyst Richard Gardner said in a report Tuesday that sales in Europe have been the only bright spot for PC sales but noted that just 20 percent of Apple's sales come from Europe.
News.com's Joe Wilcox contributed to this report.