ATI Radeon HD5770 not working on Mac partition
I have a Mac Pro 3:1 (early 2008). The orirginal 2600XT graphics card that came with it broke so I replaced it with a flashed HD5770. This worked fine for a while (except for the HDMI output didnt seem to work properly). The majority of the programs that I use now are windows only so I have set the computer to automatically run windows at startup - this works with no problem. However when I try to choose my startup disk (by holding alt at startup) to get onto my original mac partition I get nothing from the graphics card at all. I have tried all of the different outputs and also tried resetting the PRAM.
I urgently need to resolve this as I am having to sell this computer to upgrade as soon as possible.
Any help would be greatly appreciated.
[Edit: My Mac parition is running Snow Leopard 10.6.3]
Mac Pro