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Paper Tape
Posts: 2
Registered: ‎05-03-2015
Location: Indonesia
Views: 495
Message 1 of 1

Z40-75 CPU stuck at at lowest frequency 1.06 Ghz

My Z40-75 AMD CPU is always stuck at its lowest frequency (1.06Ghz) when returning from sleep. It also happened sometimes when I plugged/unplugged the charger.

I had observed this issue happened both in Windows 8.1 and LInux OS. The current workarounds are rebooting the system or add kernel boot parameter with processor.ignore_ppc=1 (LInux only). Based on the current Linux kernel implementation and previous bug stated here (, cause of this issue is BIOS bug which set cpu_freq bios limit incorrectly on several occassions (e.g sleep, charger plug). Kernel param processor.ignore_ppc=1 is set to ignore this bios limit which is not recommended either because it also bypass the hardware BIOS management.

This bug is quite annoying because when I worked in Windows, I cannot set system to sleep or I must reboot the system.

I have also updated the BIOS with the current version (33) but bug still exists. Lenovo, please fix this!

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