My Dell Rugged 5424 behaves normally on battery, with the CPU boosting to roughly 3900–4200 MHz. After connecting the OEM 90 W barrel charger, it runs normally for about 15 seconds and then becomes capped at 400 MHz. At the same time, a buzzing sound from the batteries stops. Charging is unreliable, and the batteries sometimes continue draining while the laptop is connected to AC power. Both batteries report poor health.
The processor stays around 46–48°C, so overheating does not seem to be the cause. The issue occurs in both the UEFI firmware and Linux, which makes a software problem unlikely. Disabling C-states has no effect. If Intel SpeedStep is disabled, the CPU remains at around 1900 MHz on both battery and AC, but it cannot boost to higher speeds.
What could be causing this behavior, and what hardware or power-related troubleshooting should I try?
1 Answer
This usually means the laptop is detecting an inadequate or faulty power source and deliberately limiting the CPU to around 400 MHz to reduce power draw. Even though you are using the correct Dell 90 W barrel charger rather than USB-C, the charger, DC jack, charging circuit, or battery system could still be failing. Since the batteries are unhealthy, charging is inconsistent, and they sometimes drain while AC is connected, I would test with a known-good genuine Dell charger and inspect the connector and charging hardware. The fact that the behavior also occurs in UEFI strongly points to a firmware or hardware power problem rather than Linux.
It is not a USB-C setup; I am using the original Dell 90 W barrel-style adapter. I will still test another known-good Dell charger and check the charging connection.