I'm running FCP7 on a MAc Pro with 3 monitors from 2 video cards. Two of the monitors are for the app and the third monitor, an HD TV is for video out. I upgraded from 10,6.7 to 10.6.8 and lost the ability for video out on the 3rd monitor, so I went back to 10.6.8. Does anyone know if upgrading to 10.7 Lion will cause the same video out loss or will multiple monitors work.
I don't want to partition a drive, but would like to keep current withMac OS if possible, but don't want to lose the third "video out" monitor.
There is no reason to upgrade beyond SL 10.6.7 . As you have discovered 10.6.8 has problems with graphics card drivers. FCP7 is now EOL so Lion will break it eventually. You could install a second boot drive if you want Lion, but leave the SL and FCP install frozen in time.
Running two graphics cards is a bad idea in an FCP setup. Also the feed to an external HDTV will not be accurate for grading purposes nor for monitoing interlace issues. Decklink make some really cheap cards to output a proper signal to an HDTV. And they give you a high quality input signal if you ever need to capture from an external source.