Changing from NVIDIA GTX550Ti to RADEON 6850 - problems

[namio]

Hi
I wonder if anyone here can help
I was recently advised that using the radeon HD 6950 would be a better card to use for final cut pro instead of the NVIDIA GTX 550Ti I currently have installed
So, I got a XFX HD 6850 yesterday and installed it into my machine
I updated to 10.74 and the latest Chimera before i swapped the cards out and everything was working fine
First thing I noticed when I booted up with the new card installed is that it is notably louder than the 550
The Chimera screen appears and then I am able to get into the grey apple logo and the spinning wheel but it all locks up after about 45 seconds
I have tried booting in safe mode, single user, and verbose mode...when booting in safe mode i seem to be able to get a bit further along with the install but before you actually get to the desktop and while the apple logo is still there, the screen produces multiple artifacts and locks up again
I have also tried booting the machine with r-boot and the boot process locks up at the same point as it does with the regular bootloader
I ended up putting the NVIDIA card back in and everything is working fine again now

So, a couple of questions - should I have removed any NVIDIA related stuff or enabled any RADEON stuff before i put the new card in and tried to boot the computer

If anyone here is using a radeon card or has done something similar (swapped from NVIDIA to RADEON) did you experience similar problems...if so how did you solve them?

If anyone is using final cut pro - does the 6850 really make that much of a difference in comparison to the GTX550Ti?

I have built a few hackintoshes over the years and have always avoided radeon cards because I have never been able to get them to work properly and i have never really had any issues with any NVIDA cards. This is the first time I have tried a radeon card in hack for years...I was hoping things might be better, but evidently not (at least for me)

Can anyone help/advise?

 

[dddirtman]

radeon cards are still problematic
you may have to put the card id in the radeon driver(kext)
you may also have to select a frame buffer setting(aticonfig=bulrushes)< ?not sure
generally graphicsenabler=no(at least thats what I've read)i use nvidia
because of these issues...
note: i believe (bulrushes)is for the 6870 card but it should work