I looked at the specs on your motherboard and see that it is a micro atx board. Is this rig also installed in a micro case? If so I would look seriously at heat issues. Unless your using a liquid GPU cooler your going to need a lot of clean air flowing. When was the last time you cleaned the dust out of the case and from between the block fins either with an air compressor or canned air. Worked on a computer once that was so full of dust it failed to even boot. Cleaned the dust out and it started right up.
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