So you need to set the temp properly based on the Bitmain documentation the PCB max temp for s19 is 80c you can set the dangerous temp to 75c and hot temp is 70c or below.
Braiins OS is more conservative than other firmware for good reason. Anything temperature related in Braiins OS = "Chip" temp, that means PCB+15, so if you think 80 is the max, this in Braiins OS means 95. As you know, the actual Dangerous for Brains OS is set lower than stock, to 90, and HOT is set to 80. This is because the time response of the sensors is slow, so you don't want to risk it and be on the safe side. Also, there are only 2 to 6 sensors per hashboard, so it can develop hot spots unnoticed until its too late, even more reason to play it safe and not mess with those values.
Lowering the values is OK, but never increase those. Target 60, Hot 70, Dangerous 80 is OK if you want, or you can leave it at defaults. Due to the aforementioned, leaving the 10° margin between each value is highly recommended.
In short, the best setting is already set as defaults. Enabling DPS is ok if you expect not being able to control the heat in summer/day, but a good cooling can keep the miners at constant temperature at any season any hour. Logically fans would run to nearly 100% during the hottest moments and slower otherwise.
Since DPS triggers at HOT, lowering the value to 70 is a good idea, so efficiency doesn't suffer as much (side effect of the S19 chips: hot = worse efficiency).
