John Doe wrote:
> The error message:
> Windows - Registry Recovery
> One of the files containing the system's registry data had to be
> recovered by use of a log or alternate copy. The recovery was
> successful.
>
> The system:
> OS, Windows XP SP3 with patches
> motherboard, Gigabyte GA-EP45-UD3L
> CPU, Intel Q9550
>
> The apparent cause:
> BIOS settings
> C2/C2E State Support
> C4/C4E State Support
>
> Enabling the subsetting (C4/C4E State Support) obviously corrupts
> the Windows registry. Using Performance Monitor, the graph for
> Physical Disk Idle Time tracks at about 30% instead of 100% when
> the system is idle.
>
> Enabling the prior setting (C2/C2E State Support) is not so
> obvious (unless there is somewhere to look for the sign), but it
> is deadly on my system. Enabling it apparently corrupts the
> registry and/or other files and eventually can lead to much
> crashing.
>
> Reproducing the error or telling that the corruption exists has
> been done by removing Device Manager IDE controllers and then
> rebooting.
Don't use low-power (sleep) modes defined that did not exist or were not
supported at the time the OS was developed and originally released.
You didn't bother to mention WHERE in the BIOS (screen, settings group,
etc) you are changing these settings. I had to GUESS that you were
talking about the sleep mode and the processor states available in the
selected sleep mode. I don't even see the C4 power state defined in the
ACPI 4.0a spec that was released April 5, 2010 (See Processor Power
States, page 307). C3 is the max specified there.
http://www.acpi.info/DOWNLOADS/ACPIspec40a.pdf
See "Processor Power States", page 307.
Page 312:
8.1.5 Additional Processor Power States
ACPI introduced optional processor power states beyond C3 starting in
ACPI 2.0. These power states, C4… Cn, are conveyed to OSPM through the
_CST object defined in section 8.4.2.1, “_CST (C-States).” These
additional power states are characterized by equivalent operational
semantics to the C1 through C3 power states, as defined in the
previous sections, but with different entry/exit latencies and power
savings. See section 8.4.2.1, “_CST (C-States),” for more
information.
So what was the actual *default* value for this BIOS setting? Why did
you change it? Why are you playing with BIOS settings (to change away
from the defaults) that you don't understand?