You need to install the latest BIOS for your motherboard from: -de/motherboards/rog-maximus/rog-maximus-z790-hero-model/helpdesk_bios/ After that, disable CEP "CPU Enhanced Performance". It should run stable afterward. Undervolting is very, very difficult. Actually, if the motherboard manufacturer has AI, they should be able to set it automatically. Undervolting with a 14900k takes a long time to find a stable setup. Everything can become unstable.