I recently bought power supply for my Dell XPS400 - new unit is OCZ GameXStream OCZ600GXSSLI 600W ATX12V SLI. After replacing the unit all I get is blinking amber light on the main power button. I tried number of things, using paper clip to short green and black wire on 24 pin connector (ozc support suggested to see if the fan will turn on) and connecting only hard drives did start the fan on the power supply. After that I was adding one by one component to the system to see at what point the power supply will stop working and it was at the end when I connected the motherboard that power supply didn't work any more. My computer works with the original power supply so it's not motherboard that's a problem. OCZ people say that power supply seems to be working fine but maybe it is not compatible with DELL. Dell support don't have an answer and want to sell me their power supply. I also tried taking memory and battery out and it didn't help.
I've red that people have changed original PSU on their XPS400s and wasn't sure what else I can try.