Computer Won't Boot from Any Media

So, I’m pretty sure this is a complication arising from me transferring cases, but I can’t quite figure this one out.

At first I thought the hard drive was shot because it wouldn’t boot from that, but now I’m finding that it won’t boot from my Windows 7 DVDs or Ubuntu live CDs either (both stall out just during/before their respective flash screens).

My amateur diagnosis is pegging my motherboard (an MSI 790FX-GD70) but I’d like to have more to go on before calling technical support.

Any ideas?

Let me know if you need any other system details.