Hello, after much searching, i have decided to ask a direct question about my mac (PPC G5 2.3 DP, 5 Gb ram), as it is doing my head in. I bought it a few months ago without a hard drive, put one in, installed tiger and it worked fine, then it stopped. After some troubleshooting I replaced the PRAM battery and again it was working. I installed leopard and for a few monts everything was hunky-dory, until I plugged my iPhone in to it to get the iOS update, at which point it said it needed to update leopard. as it was restarting, it kernel paniced, and ever since it will not go past the grey screen with apple logo not even a spinning gear, neither from the hard drive or from the DVD. also holding down C does nothing. I held it down long enough for the mac to go in to failsafe mode. I have replaced the hard drive again (as the one in it originally was a bit funny in the previous computer it was in), zapped PRAM & NVRAM, reset open firmware (reset nvram, set defaults, reset all). I thought it might be a problem with the DVD drive, but holding option down brings up the OS X DVD as the only boot option (the hdd isn't formatted yet). there are no light on the logic board and the power light is solid white. I have also tried swapping round the RAM. I think I've covered everyting, any help would be greatly appreciated. sorry, I should have mentioned that the power light is solid white when on, it's off when the computer is off and plugged in.