You are attempting to exceed your RAMs rated frequency and this is never guaranteed. Although not all 2700X CPUs can reach a 4.2GHz Overclock, many can with the correct cooling and 70C with Vcore at 1.308V is very good.(keep vcore as low as possible)
With a few more Bios tweaks, (LLC,SOC etc) Try for 4.2GHz and see how you go under load as I think your cooler would cope.
We owe our existence to the scum of the earth, Cyanobacteria
My System Specs:
MB:ASUS ROG Crosshair VII Hero/WiFi GPU:EVGA GTX 1080 sc PSU:Corsair AX-1200i
CPU:AMD R7 2700X Cooler: Corsair Hydro H115i Case: Corsair Carbide 780t
Memory:G.Skill TridentZ F4-3200C14D-16GTZR SSD:Samsung 500GB 960 EVO M.2
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