check the backplate again on the case?
You did install the motherboard standoffs, right?
Did you make sure the 4 pin motherboard connector is firmly plugged in?
Yes, but that's not an issue, right?
yep
well when I changed mobos I swapped back plates, and same issues both time, so i doubt that's it, but I may check it just in case.
Yep, I was plugging it in and out multiple times, I'm pretty certain it is/was in good.
Did you ever manage to do a boot outside the case? Just to eliminate any possible issues being caused by the case in some odd way, other then that you tried/tested just about everything.