The company said it has received 100,000 orders for the high-end desktops, which were unveiled in June. Apple has started shipping 1.6GHz and 1.8GHz single-processor models; a dual-processor 2GHz model is expected to ship by the end of August, fulfilling the company's pledge to send out the machines this month.
Apple is counting on the new machines to improve Power Mac sales, which have lagged in recent quarters. Last quarter, the company sold just 156,000 Power Macs, down from a peak of more than 400,000 a quarter in early 1999, and down from 211,000 units sold a year earlier.
"Our Power Mac business has needed this kind of boost," said Greg Joswiak, Apple's vice president of hardware marketing. In addition to the 100,000 orders for the Power Mac G5, Apple has continued to sell a lower-cost version of the Power Mac G4. "We've been selling G4s in the meantime at $1299 (£816.52)," he said. The Power Mac G5 starts at $1,999 for the 1.6GHZ version.
Sales of the Power Mac are critical for Apple because of their high profit margins and because they are used by graphics and music professionals; a key market for the Mac. Apple had warned that its overall profitability would be in jeopardy if the company didn't improve its Power Mac sales.
"If future unit sales of Power Macintosh systems fail to partially or fully recover, it will be difficult for the company to improve its overall profitability," Apple said in a December filing with the US Securities and Exchange Commission.
Joswiak said Apple has been unaffected by problems that IBM has been having with low yields from its East Fishkill chipmaking plant, where the G5 is produced.
"Our stuff has actually been going rather well," he said. "They've been doing a great job supplying us with G5s."
Although the Mac operating system remains 32-bit, Apple said the machines are shipped with a new version designed to take advantage of some of the G5's 64-bit processing abilities. In particular, version 10.2.7 of Mac OS X has math and vector libraries that are optimised for the 64-bit chip, as well as the ability to address more than 4 gigabytes of physical memory, breaking through a limitation of 32-bit chips.
Application developers can recompile their programs to make further performance gains, Joswiak said. Adobe Systems' Photoshop is among the programs being tweaked to gain an additional speed boost from the G5.
