I have a Late 2006 24" iMac that seems to startup fine, BUT the screen is dark. Connecting to an external display also has a dark screen. I can toggle on voice over and hear that everything seems to be fine. This seems like a GPU problem, but I would like some sort of verification before buying a new GPU for it. It is a family member's iMac, and he really cannot afford to waste money, so I cannot be wrong and buy a $300 GPU for it (about $190 used on eBay with 90 day warranty). The thing is I read that Target Disk Mode can be used for troubleshooting. I can TDM into it, but I wonder if there is any way to read error logs or something to actually find any sort of errors reporting that might definitely indicate the GPU or something else??? Any help will be greatly appreciated.