Past posts certainly show that this board has a litany of issues, though I haven't found this one in older posts:
I needed to put a different brand of Radeon HD 6570-based PCI-E card in the system so that I could use the existing card (a low-profile model) in an unrelated system that required it. I figured this wouldn't be an issue, since while the cards are different brands, they're functionally identical. Neither even uses a separate power cable, they're that low-end.
However, when I use the PowerColor AX6570 1GBK3-HEV2 instead of the SAPPHIRE HD 6570, the system doesn't boot. LED reading shows 15, which means that it stopped around LAN device initialization (I've seen people report this in the past with other scenarios). The LED strip never illuminates the 7th one, which is what it should if video is working. It gets as far as the 5th and 6th (processor and memory).
Even though it didn't make sense, I checked out the video-related BIOS settings (with the old card in), and the only thing to change was the one pertaining to the primary video adapter. It was on Auto, so I put it on the specific PCI-E item. Of course, that made no difference.
BIOS: 0028 (certainly not going higher with Sandy Bridge)
Rev: AAG30742-401
