Barefeats and Xlr8yourmac report that the ATI Radeon 3870 video card will make its debut for the Mac Pro by the end of May.
We have received confirmation from a reliable source that a ATI will definitely offer a retail version of the ATI Radeon HD 3870 with 512MB DDR4 that will boot OS X on both current and legacy Mac Pros. It will, of course, boot Windows XP or Vista in your Boot Camp partition. And, like the 2600, we expect it to support CrossFire mode under Windows if you have two installed and jumpered.
Early evidence of the upcoming ATI Radeon HD 3870 option came from the Singapore Apple Store which briefly listed the ATI Radeon HD 3870 as a build-to-order option for the Mac Pro. The page was shortly corrected.
The Mac Pro currently only offers 3 video card options to buyers: ATI Radeon HD 2600 XT, NVIDIA GeForce 8800 GT and the high end NVIDIA Quadro FX 5600. The new 3870 card should offer a price and performance that falls roughly between the current 2600 XT and 8800 GT options for gaming. However, there have been benchmarks that suggest that even the low end ATI 2600 XT card renders Core Image effects faster than the more expensive NVIDIA 8800 GT, potentially making the upcoming ATI 3870 a better choice for "pro apps" than the NVIDIA 8800 GT (further comments from barefeats).
Available benchmarks on the internet show that the 3870 is 2.1x to 2.8x faster than the 2600 XT in some benchmarks, while the 8800 is about 1.2-1.3x faster than the 3870 in Crysis (game).
If the rumors are true, this would also provide another upgrade path for older Mac Pros besides the $279 NVIDIA GeForce 8800GT.