[HELP] 990FXA-UD5 Rev 3.0 won't post anymore

[bEd0]

Hello. I've purchased this board used, and it was working perfectly for about 6 months... One day I started the computer, everything was running, but no post, no beeps, nothing... All fans connected to the board were running, but no image, nothing...
I own a FX6300, 8gb 1333MHz kingston DDR3, 1TB seagate HD, a XFX 7770 Black Edition, and an OCZ 550W power supply.
I've tested the components in my previous motherboard (which I'm using at this very moment), and everything is working flawlessly...
I can't find anything out of the ordinary in the MB...
Thought it could be a bad bios, since I've seen many threads telling to update the bios with a lower supported processor, but rev 3.0 supports FX6300 on bios FA...
Any hints? Any tests I could perform (I only have another motherboard to test, nothing else)

[bEd0]

Also, I can't turn off the power with the power button on the rig, only shutting down the power supply

[Hanneman_213]

Since July 20th, I'm having the very same problem on the very same board (Rev 1.0). The only "hardware" change I've made recently was replacing the battery for another CR2032 one. Anyone might think on a pausible solution? Sometimes the system do POST, but after 2 minutes or so, everything goes to black and after reseting the system doesn't POST. First I thought I had a PSU problem, I bougth a new one and that didn't solve the problem. I've tried pretty much everything, run the motherboard on a anti-static surface and only with the PSU conected and nothing, it POSTs whenever it wants to.