[BongWizard]

Well normally you have to press DEL at the Gigabyte screen, but Im not sure how you can get to the MIT, because your rig hasnt been POSTing, has it? You could try using an old GPU if you have one lying around and see if it starts up properly then, in which case you'd know its a GPU problem. Also, try connecting your GPU to a separate PSU (any old one as long as nothing else is drawing current from it) and you will be able to determine if the PSU is to blame for the issue.