Your computer is working slow because the cpu is underclocking so that it does not burn it sealf out. Its overheating because its getting too much voltage.
To reset your bios on your motherboard, turn your computer on
and straight after keep pressing "delete" button on the keyboard, this should get you to the bios . Now navigate to "exit" tab using the arrows on your keyboard, then scroll down to "load setup defaults" and press enter and a dialog will pop up asking you to confirm the bios reset (select "ok") . After that select "exit & save changes" and confirm by selecting "ok". Your bios should reset now.
Don't forget to select my answer as the best answer if it helped you to resolve your issue.