So recently I bought a not functional Mac Pro 1,1 at $50 just to try to revive it for fun. It did not came with a GPU, and had a constant white light while turned on. No chime. When I press the diag button, trickle and EFI GD lights up but not GPU. Just wondering if I put an unsupported GPU, like a HD 5450, will a working mac have any image displayed or will have GPU light on? When I took it apart to clean, I found out that the heat sink compound under the MCH heat sink has dried up. Could it be that due to long term usage that the MCH could have been overheated and died? Or has anyone encountered a similar problem before?