That's a change from last October, when the iMac line was redesigned, and buyers of the the 21.5-inch iMac had the option of integrated graphics via the Nvidia GeForce 9400M. The discrete graphics options available in last year's iMac line were all ATI cards.
But with Tuesday's updates of the iMac and Mac Pro lines, ATI is now the sole graphics option on Apple's Mac desktop lineup. David Baumann, product manager for AMD's graphics division, which oversees the ATI graphics products, spoke with AppleInsider about the new lineup.
The new low-end Mac Pro, starting at $2,499, comes standard with an ATI Radeon HD 5770, with 1GB of GDDR5 memory. That's a major improvement from years past, when Apple has typically chosen to put a lower product as the default, Baumann said.
"This round they actually moved that up (and chose the 5770)," he said, "so the default is actually a very, very capable product on its own."
On the high end, users can opt for the ATI Radeon HD 5870 card, which is the most powerful GPU product ATI currently offers. It offers 2.72 teraflops of processing power via 2.15 billion 40nm transistors.
The 5770 is "basically the equivalent" of the previous generation's high-end option, the 4870 graphics card, he said. Choosing to go with better ATI graphics cards helped Apple to achieve performance up to 50 percent faster than the previous generation.
In the past, Apple has had access to early hardware, or parts that are designed specifically for the Mac. This year, it released notebooks with the exclusive Nvidia 320M GPU.
But that's not the case with this week's iMac and Mac Pro upgrades, as Baumann said all of the GPUs are stock parts. ATI made some minor technical changes to meet Apple's specific requirements, but the SKU, speeds and capabilities are all identical to the cards' PC counterparts.
On the iMac side, the entry-level 21.5-inch desktop comes standard with ATI Radeon HD 4670 discrete graphics, packing 256MB of GDDR3 SDRAM. In Windows, it's a DirectX 10.1-level product, which equates to OpenGL 3.3 support.
The rest of the iMac GPUs come from ATI's HD5000 series lineup, codenamed "evergreen." All of the cards have the same feature set capabilities, but they differentiate in terms of performance. The cards -- the 5670 with 512MB GDDR3 and 5750 with 1GB GDDR5 -- can support OpenGL 4.1 and DirectX 11.
Despite ATI's dominance on the Mac desktop, Apple, for its portable computers, has instead stuck with that company's rival, Nvidia. The last last Mac notebook update, the $999 MacBook, added Nvidia GeForce 320M graphics to the company's low-end portable computer. The 320M mobile graphics processor first appeared in April in the updated 13-inch MacBook Pro.
The higher-end 15- and 17-inch MacBook Pros also have Nvidia graphics. They include a discrete GeForce GT 330M processor, as well as integrated Intel HD Graphics. The systems intelligently switch between discrete and integrated graphics to balance power and battery life.
Despite ATI's absence from Apple's notebooks, the relationship between Apple and AMD, the owner of ATI, could expand to even greater lengths in the future, as AppleInsider reported in April that the two companies are in advanced discussions to bring AMD CPUs to its Mac line. Currently, all Macs are powered by Intel processors.
AMD declined to comment on its relationship with Apple, and Baumann simply stated that the graphics side of his company has a good working partnership with the Mac maker.