Dude, motherboard is shot. I had this EXACT problem. I started with the 790fx and a 965be last year, then few weeks later the 1090t came out, so I bought that. Continued on my merry business overclocking to 4.2, then ran linx or IBT, and BOOM, shot dead. I got so frustrated I bought a new board since it was past my return policy and i wanted it NOW
and guess what....BOOM. These boards just cant handle six cores dude. Luckily i returned the SECOND one and ran my 965be from then on.
I havent been to this forum in like a year, since I figured out my stable overclock way back when. The reason Im here now is because my 790fx apparently doesnt like the overclock anymore? I kept losing system time and one day i look at cpu-z and everything is back to stock...I was like what the hell so I put my overclocked settings back on and its not stable. Now Im starting from scratch to see what happened....I ran memtest but no errors....who knows. Ive got a thread about it, sorry I wont hijack this one. Stick with the 965 dude its just as good, unless some super Pi numbers and benchmark ratings REALLLLLY matter as much as you want them to, becuase....they dont. Play games, have fun! thats why we do this.