All PC GPU guides on XPJournal, with numbers from our own PC.
Overclock a GPU in MSI Afterburner step by step: power limit, core, then memory. Our RTX 3080 went from 199 to 212 FPS in Heaven for 51 W more.
Undervolt a GPU in the MSI Afterburner curve editor step by step. On our RTX 3080: the same 190 FPS in Heaven at 288 W instead of 316 W.