Ok, seeing as there's at least 3 threads on this topic, and I've been posting in all of them, I figured I'd create this thread to help consolidate the info we know so far. Please note, this is for *OFFICIAL* Apple Radeon 5770/5870 cards, NOT flashed cards. I'll also try to keep it updated with more info as it comes in. Also, feel free to chime in if something is wrong. Thanks! Here goes! CONFIRMED: - 5870 and 5770 work with no some issues in 2009 and 2008 Mac Pro's - UPDATE: Weepul pointed out that Rob-ART from Barefeats had some trouble with a 30" Cinema Display and a MDP --> dual link DVI adapter on 2008/09/10 models, though he thinks this may be due to a bad adapter - UPDATE 2: Rob-ART says OWC got a 30" working on MDP of 5870. (post) - UPDATE 3: grey17 says the 5770 works in 2009 Mac Pro (link) - 5870 and 5770 work in SOME 2006 Mac Pro's: - Rob-ART from Barefeats says it works. - OWC says the 5770 only works with DVI works flawlessly on 2006/2007 (MDP and DVI) (post) (confirmed by netkas), and the 5870 doesn't work at all. (link) - Those who got it to work apparently have some "undocumented" EFI version, MP11.005D.B00, though it's still unknown if that's the real reason. (post) - UPDATE: 2006 Mac Pro firmware listing and compatibility, from Rob-ART: MP11.005C.B00 -- boots 5870 and 5770 MP11.005C.B08*-- OWC has this one; they say it boots 5770 but not 5850 (5870?) MP11.005D.B00 -- boots 5870; will try 5770 Monday - In order to drive 3 displays, two MDP --> dual link DVI adapters are required, regardless of whether those displays are single link or dual link DVI. This also applies to the 2010 Mac Pro. (thread) (Apple knowledgebase support doc) - MDP --> VGA adapter considered an "active" adapter, so that's another way to get 3 displays working. (post) - UPDATE: Rob-ART says "Only 2 of the 3 displays light up -- the one on the DVI port and one on an MDP." (post) - 5770 ship date for Canadian Apple online store = Sept 28 (post) - According to Rob-ART, CrossFire connector is present on the 5770. Dual GPU tests in Windows pending. (post) - UPDATE: And the 5870. (post) - 5770's now shipping from Apple UNCONFIRMED: - "2007" (aka 8 core 2006) Mac Pro compatibility OWC says 2007 compatibility is the same as 2006 compatibility - audio over MDP and/or HDMI - Though it should work with no issues, no reports of Boot Camp functionality yet. - 5770 and 5870 reportedly available from MacConnection.com starting Fri Sept 10 17, Tues Sept 21 from MacMall.com - "Active" single-link MDP --> DVI adapters are apparently coming soon for ~ $30 US. Might these be an alternative to the $99 US MDP --> dual link DVI adapters? (AnandTech) - Dave Baumann from ATI tweeted about active DisplayPort --> single link DVI adapter now available at NewEgg.com. MDP version soon?