After following the instructions from z970, I successfully flashed an X1900 GT with the firmware from The Mac Elite, and it boots in my Powermac G5. The only problem is I am not getting any video on my 30 inch apple cinema display, the white light just flashes slowly. I tested with a Dell monitor at standard 1080x1920 resolution and am getting a good display. With Dual displays, Dell and cinema I get a display on the Dell and the cinema remains blank.
Has anyone else seen this issue? I'm assuming it's a driver issue. I tried both 10.4.11 with the ATI drivers installed, and 10.5.9 Sorbet Leopard with the same result. My mac is correctly identifying the card as ATI Radeon X1900 GT with 256 MB of VRAM. Obviously, I want to use my G5 with the 30 inch cinema, and the X1900 GT should support 2560x1600, so theoretically it should work. If this is not possible with the X1900, is there a video card besides the stock one that can?