My Gene-Z does same thing with the IB supporting bios and either 2x4 Samsung or Hynix sticks (no probs with 2x2 Hypers). System kept rebooting at any mem speed over 1333 no matter what timings/vdimm. The solution for me was disabling the Memory bandwidth booster option. When disabled even 4x4 at 2133 is good to go :up: