possibility that S5 is influencing the higher temperature but to rule that out, you can move S7 into another air conditioned room and power it up and check the temperature.
If in colder air conditioned room and 1 pcb is showing still hotter temperature, then, time to open the unit and see if cleaning be needed. We have seen many units with temperature problem had everything you can think of collected and saved on the hash PCB and inside the S7 case.
dust, human hair, animal hair, hairball, candy wrappers, parts of vermine, insects. So dust off may help if that is the case.
If dust off and in the cold room and the temperature will not be resolved, then please check the intake fan, if it is spinning at at least 3600 RPM.
if none of those solves the problem... then you probably have some chips or components that are degraded but still function. At this stage, not sure if its cheap enough to repair or seek used S7 and replace the parts or let it go
Repair on S7 pcb can cost from $35-$85 range some are less and some are more.
about a month ago I got a used S7 that has run ok for now. However i've had to reboot a couple of times and I suspect it's because it went over 80C and stopped.
I check the board temperatures and one is running at 70-71C while the other two boards are running at 62-63C. Could this be an indication the miner needs a dustoff ? I'm running it next to an S5 (about 4 inches apart) so my other thought is that maybe the S5 is generating heat that is conducting to the S7 board closest to it. The S5 boards are running at 56-65C.
Thank you for any help you can provide.