XFX motherboard problem

I just got the XFX 780i which replaced my EVGA 780i which i have to send back to the company because its broken, but anyway, I swapped motherboards and everytime I turn on my computer, I dont get any picture (which i dont understand why).

****Also****
I get a little red light underneath my cpu heatsink plug (which I also dont understand why)

Any thoughts?

Thanks

In addition to the 24-pin ATX power connector, make sure the PSU is also connected to the 8-pin ATX_12V power connector. I assume you're also seeing a FF POST code on the MB LED display?