MSI Afterburner is not available for Linux but there are some alternatives that runs on Linux with similar functionality. The best Linux alternative is MangoHUD, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to MSI Afterburner and seven of them are available for Linux so hopefully you can find a suitable replacement. Other interesting Linux alternatives to MSI Afterburner are CoreCtrl (Free, Open Source), GOverlay (Free, Open Source), GreenWithEnvy (Free, Open Source) and WattmanGTK (Free, Open Source).
CoreCtrl is a Free and Open Source GNU/Linux application that allows you to control with ease your computer hardware using application profiles. It aims to be flexible, comfortable and accessible to regular users.