Before overclocking, you will want to ensure you have a high-end cooling solution to keep 16 and 18 cores out of thermal trouble. I usually use a Corsair H115i as my cooler, but even as good as it is it cannot handle the thermal load of the Core i9 7980XE or Core i9 7960X with any added voltage. Stock voltages were in the 0.89v range, but it took voltages of 1.12v to 1.14v to get the processors up to 4.5GHz. As low as those voltages are, a custom water cooling solution was taxed to keep thermals in check when running Prime 95 workloads. Under most workloads, the processors would stay below 85