Have you done any overclocking yet? I use my ivb-e cpu with r4e since its lauch. Extremely stable. 1.24V 4.5G. Now testing with r4be, my computer shut down instantly during p95 test, increasing vcore to even 1.3v, still shut down instantly. Besides, I notice the voltage reading of vcore is incorrect from adia64, HWiNFO64, even asus probe. do you have such problem?
Others have noted the same thing, try increasing VTT and VCCSA voltages if you are running XMP/overclocked memory.
Also some have noted that any setting other than auto for LLC will result in reboots which seems to be a bios bug.