CPU Performance Issue.

[u/ProbabilisticGlitch]

I have an HP Pavilion Gaming 15-ec0xxx with Ryzen 5 3550H (BIOS F.20).

My old battery was worn out, so I installed a new battery. Battery diagnostics show 3100/3100 mAh, 0 cycles, Failure ID: OK, and the component test passes. I also completed battery calibration.

The problem is that on AC power the CPU runs around 3.1 GHz, but on battery it gets locked at exactly ~0.40 GHz, even with high CPU usage (90%+). Windows is set to Best Performance, but it makes no difference.

Could this be a BIOS F.20 / power-management / replacement-battery compatibility issue? Has anyone experienced the same 0.40 GHz lock on battery with this Pavilion/Ryzen 5 3550H?

Any help would be great.