why? what's wrong? OCing problems?
Yes it is unstable at the same settings which have been tested stable with F3. I only spent about 30 minutes with F4, so who knows. I can't run faster than 150 Bclk 44x QPI / 24x Uncore with safe voltages anyway.
I pose this question: Will F4 run faster with different Bclk and multis? No time to try it myself.