Since you replaced the motherboard, and tested all RAM, it seems to be a processor issue, so I would suggest calling the local Intel technical support center at:
It would be a good idea if you can take your processor to a local computer store, or to a friend’s system and test it there with a totally different hardware configuration, to make sure it is the processor.
Yeah , unfortunately , all of my friends are stuck in the stone age and don't have x58 set-ups. There aren't any repair shops here other than Best Buy and a place called Computer Reboot. They just do formatting and Spyware/Malware removal.