How to undervlot a GPU?

[nirus]

I recently bought a PC but GPU is heating a lot. So I want to undervolt it to reduce the fan noise and the temps. But I have no clue how to do it. Does it effect my performance a lot, how much volt should I lower.

 

GPU : ASRock RX570 Gaming D 

[nirus]

These are the default settings in MSI Afterburner.

 

[ImAlsoRan]

26 minutes ago, nirus said:

-snip-

Here's a handy guide, the first Google result.