Hi ! I have the same problem. (First of all, English is not my native language either) I had crossfire issue with two AMD 7970m. After hours of trying things and looking on forums, someone told the cards had not the same BIOS version and his solution was to flash from the oldest bios both cards. I did it with GPU-Z for getting the .rom and used ATI Win Flash to flash both cards. After the reboot, I had the black screen issue. I tried to remove the Motherboard battery but it didn't work. What should I do ?
