gah! so many differences in opinion. before i set up this rig last month, i read this long-winded rant on another forum (which i can't find) about Spread Spectrum being preferable for Sandy Bridge CPUs. could disabling it result in lower temps/greater stability/both?
all C states are off, i had Speedstep off at first for testing but it didn't seem to affect anything when i enabled it. don't you have speedstep enabled, as per the core speed in your screenshot? i'd agree it's best left off for testing at least.
i'll go back down a few volts on the vcore, try disabling Spread Spectrum first, then if that doesn't work reset the RAM timings & i'll let you know how it goes. cheers!