According to CPUID CPU-Z and Windows Vista resource monitor the AMD Sempron 3500+ (1800MHz) in this Packard Bell Easynote SJ51 is never clocking higher than it's lowest speed. It's running at 52C so it's not overheating (other components also report around that temperature).
This also happens in 'high performance' windows power manager settings (with min/max CPU set at 100%, as default). The system is plugged into the charger.
Notebook Hardware Control (http://www.pbus-167.com/nhc/nhc.htm) shows there are states O1 (1800MHz), O2 ,O3 (800MHz). There's also a setting "scaling allowed" which is set to 'No', but changing it doesn't appear to do anything.
How do I debug this?
Edit: BIOS update to 1.0g enabled p-state transitioning, CPU-Z now shows higher MHz states are entered. Sadly there is no changelog to be found, since the machine just want to Vista SP2 (still at 800MHz) and then was updated futher along, it might be something other than the BIOS.