adambk
Your power supply should also have a 24 pin connector, which powers the CPU. Make sure that both the 4 pin and the 24 pin are connected and try again.
Also, while I'm glad to help, I think you're posting on the wrong forum. This is Blackmagic Design, maker of cinema cameras and other pro video gear. I found a few PSU's with "black magic" in the model name, which may have led to some confusion, and just wanted to make sure you were aware that this is not the same company.