GPU gets hot by basic tasks

[Lachs49]

My GPU is a AMD Radeon (TM) RX 480 Graphics.

Idle temperature is 30-40°C but it jumps to 90°C almost immediately running old games at 25% workload and shutting down completly trying something newer.
The Fans are working and cleaned, I applied new heat paste und the airflow is good.
The GPU just seems like it doesnt get cooled as the fans go wild but the temperature keeps rising.

Does anyone know what might be broken or what I can try?

[ngc2392]

Most probably gpu is broken/faulty. Try with new psu also (despite not relatable option)

[daisy]

GPUs can get hot while idle for a number of reasons including incorrect fan speed settings, graphics-heavy processes, background software, and voluntary or involuntary overclocking. The GPU overheating problem can be resolved by resetting these settings or restoring the defaults. You should also check motherboard performance. if there is any lag then consider this also. you can get more info about compatible boards with your GPU here. https://demotherboards.com/