My CPU stuck at 800 MHz

[MisterEd]

MBD: Gigabyte GA-990FXA-UD3
CPU: AMD Phenom II X4 955
RAM: GSkill RipjawsX (2x2GB)
PWR: Antec TruePower TP-650 (650W)
CASE: Antec 300 (3 120mm, 1 140mm fans)

A few days ago I replaced my case because the old case had inadequate cooling with CPU temperature ranging from 45-70C. After reassembly everthing worked fine. Now CPU temperature ranged from 35-55C.

Today I noticed that that my CPU speed was stuck on 804 MHz no matter what stress I placed on it. Normally it should ramp up to 3200 MHz when necessary.

Even when I change my Windows Power settings from Balanced to High Performance the CPU is still 804 MHz all the time.

If I go into the BIOS and disable the "Hardware Thermal Control" and reboot now the CPU speed is 3200 MHz all the time.

BTW, before I replaced my case I replaced the Artic Silver 5 on my CPU which by itself dropped the CPU temperature by 2-3C.

[DarkstaR]

Very odd effectively...is your cpu based on the c3 version ? you can see it with cpu-z soft or when reading on your box whether it's written hdz955wfk4dgm instead of dgi (c2 version -> less good: need more power and less good for overclocking).
Maybe update the bios of your mainboard and just think to enable cool and quiet and "normal" concerning the power scheme of win 7...

[MisterEd]

Very odd effectively...is your cpu based on the c3 version ? you can see it with cpu-z soft or when reading on your box whether it's written hdz955wfk4dgm instead of dgi (c2 version -> less good: need more power and less good for overclocking).
Maybe update the bios of your mainboard and just think to enable cool and quiet and "normal" concerning the power scheme of win 7...

The  AMD Phenom II X4 955 is C2 stepping. I bought it back in 2009. I am using the F5 BIOS.

I forgot I had manually set the multiplier. It is now back on auto. The CPU is again changing from 800MHz to 3200MHz like it should. Unfortunately I still can't enable "Hardware Thermal Control". When I do the CPU is again stuck on 804MHz. Also, with "Hardware Thermal Control" disabled the CPU temperature swings from 38-68C. Could "Hardware Thermal Control" be not working because there is a problem with  "Cool-and-Quiet"?

The power setting is "Balanced". Using Core Temp I can monitor the CPU frequency, voltage, and temperature.

Thinking back now last spring I had to replace my motherboard because my computer had been struck by lightning. I wonder if the CPU was damaged also and is causing me problems now.