29 Nov 2010:
There are two issues with current release of MacOS 10.6.5 Snow Leopard

PROBLEM:
ATI Graphics Card drivers have poor performance playing back hidef files
This effects performance of 4870 ATI graphics cards in OS versions after 10.6.3 and 5770/5870 which ship in macpro 5,1 Aug 2010 onwards
Also effects hidef video input.

SOLUTION:
(as at 29 Nov 2010)
Use a Mac compatible Nvidia graphics card.
Nvidia cards do not seem to be affected by the performance problem.
Nvidia GT120 (available from apple £123.00GBP / 200USD),
GTX285 (available via ebay £220GBP / 450USD.) *Preferred*

Nvidia GT120 has poor graphics performance and is not suitable to use with hidef and triple heads.
GTX285 is the best performance graphics card but was discontinued in Nov 2010 - and is currently only available from sources on eBay.


PROBLEM:
Quicktime Video input crashes from 10.6.2 onwards
This affects video capture when using Decklink AJA or Epiphan cards or USB webcams using quicktime drivers.
This does not affect Active Silicon LFG4 or Phoenix Capture cards, as they use their own drivers.

SOLUTION:
(as at 1 Dec 2010)
Catalyst v4.4 m329 has a quicktime video capture fix
http://chaldee1.gotadsl.co.uk/~richa...ead.php?t=1907


2010 MacPros 5,1 Boot in to 64Bit
New 2010 MacPros 5,1 boot in to 64bit mode.
3rd party drivers used with catalyst are not compatible with 64bit mode-
Active Silicon Drivers and other video digitisers are only 32bit.

SOLUTION:
MacPro need to boot in 32bit mode.
To select the 32-bit kernel for the current startup disk, use the following command in Terminal:

sudo systemsetup -setkernelbootarchitecture i386

This will sets the Mac to boot in to 32bit mode permanently
(an alternative command is available to boot in to 64bit mode)



NOTE:
These issues do not affect users using Mac OS 10.5.8 Leopard.
Drivers for 5770/5870 are not available in 10.5.8