Okay, here's my situation: I got a second hand Power Mac G5 2.0GHz (dual processor). It had a 160GB stock drive. I wanted to swap out the 160 for a 250 I had just lying around. I rebooted with the 10.4 system disc, and proceeded to image the 160GB Apple Partition Map to the 250GB drive. Little did I know (not until after I erased my 160GB HDD) that the 250GB drive was partitioned in Master Boot Record. My bad, I know. Now I just want to do a fresh install. Never mind the data, it's not important. But, since I have no OS on any of the drives, I'm trying to boot from a 10.5 Disc AS WELL AS my original 10.4 System disc that came with the computer. Neither will boot. At first I thought it was the fact that I was using a keyboard that was connected via bluetooth and the dongle wasn't sending the correct signals through the USB port to the computer. Fine, I get that. BUT, I just tried to use a wired keyboard today (granted it's a Windows Keyboard), and holding down C does nothing at startup. I get the flashing "?", then the finder logo on a file folder that sits on the screen for 15 minutes, before flashing a "?" quickly, then going back to the finder logo. I've even got a secondary optical drive hooked up via firewire and it's not seeing anything there either. Now, the RAM in the unit is not the stock RAM. I do get video output through the monitor I have hooked up. Is this an issue of a logic board failure? Or am I missing something basic. I've tried everything from PRAM resets, to SMU resets, to trying to boot with the HDD's unplugged. I even tried to install OS 10.5 onto the 250GB drive via my MacBook Pro, but it won't let me partition in anything other than GUID! NOTHING WORKS. Does anyone possibly have any helpful hints or comments? Much appreciated if anyone can help. Thanks.