The voltage is low enough it might not be enough. My 5600k APU OC got to 4.4Ghz running 24/7 with 1.452v. OCCT or Prime it but my system is not OCCT stable but still can pull through lah for everyday usage.

There's no fixed value for priming/stability test. For me if the system survived 6hours of OCCT is enough but it's not a gurantee it'll be stable. Many factors to consider especially the motherboard quality and the power supply. Overclocking is one thing but for stability, you need more cash. Can't use stock cooler or the crappy power supply that came with the casing. I am using FSP 80 Gold 600W psu and Cooler Master 212 EVO dual fan push pull to achieve like 15% oc usability. Like I said my system is not stable for 100% stress test but for normal use, only 3-4 blue screen per year only.

To increase the voltage you must set it in BIOS. Learn to navigate BIOS and function of each parameter. Usually it says vcore voltage. There's a software to adjust within OS but I don't recommend using them becuase it'll crash your system. Before adjusting voltage, you can try minimum then tune to stable or maximum allowed then -0.05 the initial value to stable voltage.

This is how my Gigabyte BIOS looks like. See the CPU vcore row with the adjustment on the rightmost.