I'd treat that 127 as a placeholder, not a real reading. 127 is the top of an 8-bit signed temperature range, and it commonly shows up when the firmware polls a sensor that isn't there or isn't answering. A live sensor normally moves a few degrees with load and time of day, so if it sits at exactly 127 across reboots and busy periods, that's a strong sign nothing is being read. Your 35C on the heatsink is a better indication of how the box is doing than that log line.
To confirm the box is fine, look at the HDD temperatures on the S.M.A.R.T. or device status page. Drive temps come from the drives themselves, so they're a more trustworthy airflow check. If those look sane and the fans aren't pinned at full speed, you can ignore the mobo line.