Older Mac Pro users beware of Mountain Lion upgrade

Question

I work at a company where we have 6 edit suites. Five of those suites are still running Mac Pros; three of them are Early 2008 models, two are Early 2009 models. All of these suites have 30" monitors in them running at 2560 x 1600 resolution. The other suite has a new 27" iMac. All but one of the Mac Pros have their original graphics cards.
When Mountain Lion first came out, I upgraded my Mac mini at home that has FCP7 and FCPX installed on it. Both applications ran fine and I was able to edit a project in FCPX with no problem. A co-worker who works remotely on a 27" iMac had also upgraded his machine and experienced no issues.
Seeing no issues with the ability to run FCP7 under Mountain Lion, I proceeded with upgrading the MacPro suites at our office. After an initial test on one machine to confirm that FCP7 would load and launch projects, I proceeded to upgrade the remaining suites. It soon became apparent after other editors began to use their computers that FCP6 and 7 were affected by the upgrade to Mountain Lion.
While the programs still work fine, one fundamental change that Apple has made in Mountain Lion is to push more of the responsibility for displaying the image on the computer monitor to the GPU of the graphics card. Previously these responsibilities were shared with the CPU. Therefore, if you have an older graphics card (even if it is fully compatible with FCPX, as ours are), FCP6/7 has a difficult time playing back 1080 video in the Canvas window (at any size), without breaking up when there is some degree of movement in the video image.The screen cannot refresh quickly enough to draw the video image without showing horizontal banding and some minor digital garbage.
Rest assured that the render files are clean and the output file will be fine. Once exported, a self-contained .mov file will playback fine in Quicktime, showing no banding where there previously was banding when viewed in FCP. This is an issue with display only. If you can live with it, fine. But it is rather distracting while editing.
I attempted to downgrade one of the Mac Pros to Lion earlier today. While I was able to successfully downgrade (not with a clean install, but another method), both FCP7 and FCPX would no longer launch because they were confused about which version of the OS was running. Using FCS Remover, I deleted both FCP7 and X, then reinstalled FCP7. Still no luck with launching FCP7. I finally decided to reinstall Mountain Lion for the time-being. FCP7 now launches again.
Just a warning to those considering upgrading that you may experience performance issues with FCP6/7 if you are using an older Mac Pro and trying to edit 1080 footage. You may have to upgrade your graphics card to achieve best performance.

Answer 1

Christian Castagna1 wrote:
Yes, we previously we had purchased an ATI Radeon 5770 to enable use of FCPX, and 1080 video plays fine through that in both Early 2008 and Early 2009 models, although it is not fully compatible with those computers. Technically it is only compatible with Mid 2010 Mac Pros. It is unclear if there is a card that is fully compatible with Early 2008 computers and FCPX at this point.
We have noticed some small pixelation around the edges of icons with the 5770 in an Early 2008, but that is intermittent and goes away with a restart. We have not noticed any issues in the Early 2009. We have also just purchased a Radeon 5870 and will be testing that in Early 2008 models to see if the same pixelation issue happens. We will install that card eventually in an Early 2009 computer because it is fully compatible with that machine.
If nothing else, hopefully these graphics cards buy us a couple more years with our Mac Pros.
Can you explain a little more about this please...  My primary system is a 2008 8X 3.2GHz system with a ATI Radeon 5770 and I have it running two 27" Samsung monitors and a 37" HDTV (all 1080p) on FCS3. None of the displays have any artifacts under any conditions. What are the compatibility issues? If I'm doing a no-no, I want to know before my next big project...