Maybe it's too late to help but if your reboot problems continue, I resolved mine with set RAM frequency to 1066 even if original frequency is 1600.
I have no more reboot.
You know what, you are bang-on. Shortly after I posted that message I realised it was the DDR that was not set to "Extreme Memory Profile" and I had it manually set to 1866Mhz. I noticed by doing this it changed some of the voltages and timings automatically, and it hasn't crashed since!
Apologies to Intel for doubting them.....
To err is human, but to really foul things up requires a computer. ~Farmer's Almanac, 1978