I've recently gotten a few footlong USB PCI-E risers. BAMT is not able to see cards on them. I've tried the same cards using older, ribbon-style risers in the same slot and they work. I've also tried USB risers from 2 different batches and have the same bad results. Even the green "power" LEDs on the back of the 280x card do not light up when the system is off and cards plugged into PCI-E slots via the usb risers.

I'm using an ASRock 970 Extreme4 mobo with a 1200W Gold PSU. Anyone experience this before?

Honestly, it's BFL. Nothing surprises me anymore. They're the epitome of sleaze.