Lower temperature is always better. Anyway, you can read more on CM4 temperature here - https://datasheets.raspberrypi.com/cm4/cm4-datasheet.pdf
The BCM2711 will reduce the clock rate to try and keep its internal temperature below 85°C. So in high ambient
temperatures it is possible that the clock will also be automatically throttled back. If the BCM2711 is unable to lower its
internal clocks enough to bring the temperature down, its case temperature will rise above 85°C. It is important that any
thermal solution chosen keeps the ambient temperature for the other silicon devices on the CM4 within the operating
temperature range.
Operating temperature range: -20°C - +85°C non-condensing. NB Optimal RF wireless performance is between -20°C and
+75°C.
