meh. there are chips out there that can do 5.0 GHz at that voltage.
Nice that you got a better chip than you last one, but your last one was garbage, and this one is just slightly on the good side of average. my review chip did 4.6 GHz @ 1.184V, 1.220 for 4.7 GHz, 1.275V for 4.8 GHz, provided it had the right board and cooling. That was an early retail chip bought locally.
That's why you had issues clocking memory...you had a shit chip.
Try for 5 GHz, that's the clock to "bin" IVB with. You got the thermal overhead to do it on your cooling. Max temp is 105-110c on IVB, just keep it under 100C under P95/IBT-type loads.