I'm working on an 21.5" early 2006 iMac for a friend. He gave it to me with a bad hard drive which I replaced with a WD Caviar Black 500gb drive. However since the replacement, I have not been able to get any video from the iMac. I've tried with the iMac screen and the corresponding adapter. I'm wondering what the issue could be? My thoughts so far: 1. Power supply - I'm not getting anything at all. The Led does not glow when plugged in, however the Mac appears to be booting correctly. [can't say for certain no video]. 2. Video Card since - no getting any output. What I have tried: 1. Reseating cables several times over. 2. Reseating the ram. 3. Putting the old HD back in; this still doesn't show any video. I've worked on a Mac Mini before and work in hardware support on PCs, so I do know my way around. However, I'm pretty stumped with this issue. Any help / suggestions will be appreciated.