Netkas strikes again with drivers for the 4850. How? that's a secret for the few, which certainly doesn't include this reporter, but a few bugs aside, (need switchresx to set widescreen resolutions, and some port recognition issues) It appears to work well.

Apparently the official word is "4870 works great, 4850 stutters (graphics lag, like 10.5.6 with 8800GT, but sometimes worse), and 4830 doesn't get QE/CI yet"

The problem is with PowerPlay - it decreases the memory clock if you're running apps which only require 2D hardware acceleration. After BIOS flashing your 4850 in order to bump up the memory clock to 993 MHz, it works. I even removed SwitchResX and my monitors native resolution (1920x1200) is recognised (plus a few other widescreen resolutions). A problem with this method were a few visual artifcats: http://img.skitch.com/20090301-kwgkteka2yy...7cpmx8ga5wc.jpg

So the alternative to flashing your card is to use Netkas' modified Natit package which uses aty,bin_image to reference a modified BIOS dump. Or you can just disable PowerPlay completely by putting:



into Natit's Info.plist (again, thanks for Netkas for this this code). I have not tried this method however, so cannot guarantee it works. I'm currently using Netkas' Natit with included BIOS which does the trick nicely - the only thing that is not working is dual display and sleep (I have yet to try the other DVI port - I don't think it will work though). Also - you need a DVI => VGA adapter hooked up to the other port (no need for it to be hooked up to the monitor). However, I don't understand why we need this at the moment.

Edit:



Edit 2:

http://www.macrumors.com/2009/03/03/last-m...e-and-mac-pros/
http://forums.macrumors.com/showthread.php?t=660492

Apparently the Mac Pro will support a HD 4870 buy-to-order upgrade. This would definitely help all HD 48x0 users...