If you experience "Device is running too hot! Performance is degraded!" error in Excavator, it mean that your GPU is thermal throttling due to overheating.
This error only shows when the device is thermal throttling due to overheating and it should be acted on immediately. The GPU can thermal throttle due to high GPU core temperature or too high VRAM temperatures. High VRAM temperatures are common with RTX 3000 series.

Possible solutions:
Read this blog article about overheating GPUs.