Originally I had Crossfired a Sapphire ATI HD4850 512MB and a XFX ATI HD4850 512MB and that worked well except that the XFX card would idle at 41 degrees F and the Sapphire would idle at 74 degrees F which to me was too hot. I got a XFX HD4850 1GB to replace the sapphire (I got 1GB cause I was impatient) and now I cant play games! everytime I try to start one up it says "Display driver stopped working and recovered" and then it talks about atikmdag... Is there anyway I can fix this problem?
you probably need to reinstall your drivers, even though you had a previous crossfire setup lots of times windows will not detect the new device correctly and screws up the old drivers.
I also think like belial that your drivers are screwing your setup. Also, hybrid crossfire isn't something I am too fund of. It would have been a great idea if it was using the full ressources of the 2 cards, but slowing one down to operate like twins isn't my cup of tea...