10sep2010
The latest mac pro 5,1 - just about shipping -is currently broken out of the box- drivers for 5770/5870 are broken

10.6.4 is has huge problems too - its seems with ATI video cards- particularily the radeon 4870 - which was mostly broken for large texture uploads on 10.6.4-

Apple released a graphics update for 10.6.4 a couple of weeks ago- which made things better

but this doesnt work on latest mac pro- yet-

There are reports of other graphics cards working - nvidia cards seem to be working much better

10.6.5 isnt out yet.

10sep2010