I have 2 computers with the same startup issues. Both of them hang up upon booting. The Apple logo shows up on the screen, and that's all (folks). If i wait a minute or two, the fans start speeding up to their maximum rpm, but nothing happens. I've tested all the memory modules, the hdd, the optical drive. I've even replaced the videocards. Nothing wrong with any of them. One of the machines is a dual cpu 2.0 GHz and the other one is a dual cpu 2.3 GHz (dual cpu, not dual core, my 2.3 dual core still kicks butt). I have taken the 2.0 apart, to take a look at the power supply, since this is the only easy serviceable thing left in the machine that i haven't checked. It's in mint condition. It had a lot of dust bunnies, but no bad capacitors or any other problems. I have the feeling that the motherboards might be the troublemakers. It hangs when i boot from the optical drive, or the hdd. Funny thing is that the 2.3 passes the AHT. I used the AHT from the original disk that came with the 2.0 since i don't have its original disks. The 2.0 hangs when i do the AHT. Any sugestions? Maybe someone had the same problem and found a solution because, to be honest, it's quite a big coincidence that they both died the same way a few weeks apart.