yep, i always load optimize defaults after flashing bios, i think it wants 1.4v vcore now instead of 1.375v for 4ghz to be stable

but thats crap because i had it 13 hours prime stable @ 1.375v before proof is in my sig
For me this is normal. With my previous rig, Rampage Extreme/Q9550, during an entire testing week priming had a reboot at 15/16 hours. I tried with Linpack and the systems reboot into the first 5 minutes. I need to climb the Vcore three notch more for true stability. I think that a rig is prime stable only passed 24H, or 10h full mem + 10h small ftt.

@hicookie thanks for trying but it seem that i am loosing faith with this version of EX58-Extreme Motherboard.
One of the most ugly problems in this version is that coming to market many boards with a tiny capacitor blade off in the back of the mosfet circuit. Either it off when you're manipulating the board, which was what happened to me.