Rockpi4c+ overhitting and getting turned off

i have rockpi4c+ and installed Armbian 23.02.2 Bullseye with Linux 5.15.93-rockchip64. but sometimes if i run several program, it become hot and turned off (no green light and no blue blinking). How can i solve this problem?

Have you tried add a heat sink and fan to lower the temperature´╝č

yes, actually after adding heat-sink and fan it is not turning off. i did some stress testing, with stress software, and the temperature is not going more than 85 degree