This is a correction to my other post. The card i have is a zwfc not a zdfc. Updating to 10.6.4 caused QE and CI not to function. I tried replacing the ATI kext files with ones from 10.6.3 combo update using pacivist but that caused the system to halt on boot and I had to put my ati x1900xt back in and re-install 10.6 and 10.6.3 combo update to get the 4870 functioning with QE and CI. I'm not sure if my other problem when playing wow and having the system hang with checkerboard overlay after a random amount of time still exists, but if it does I will open the case and see if any of the three LED's are lit on the back of the card. I compared the rom I wrote to one Cindori wrote for the exact same card model and they appear to be the same. I didn't do a byte-by-byte comparison but checked it visually with 0Xed.