This happens even on new Dell machines, even if the PSU is detected but a lower wattage than the shipped PSU. I have wondered if it affects Linux more than windows though
A quick way to check would be to `cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq` while you're on battery, then do it again after you've plugged in the PSU. I checked mine[0] and it apparently doesn't affect this model (the adapter I tested with does not communicate with the laptop at all).
