I've been checking out the forum for my problem but can't find it. My imac dv 400 will try to boot up.. you can hear the chime and the hd power up but the screen remains black. It's running OSX.9.2.2 so it's not the firmware problem. Also, I took out the hd and dvd/rom and checked them in another computer and they are fine. I changed the battery from another imac that boots fine but it could still be low and I changed to ram I know to be good but still everything remains black. I've been told it could be the PAV board but I thought you didn't even get the chime when that went bad. Any ideas?