Rikki said:
Hi,
I have bought a new Pentium 4 3.06 GHz and I used Win2K
Professional. This processor has 512KB second cache level.
I used tweak software to optimize my processor, I need
your comment about this? is there any advantage if I
change this value? is there anyone of you have tried it
and how about the impact? because before I run this
software this default value is 0.
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Sessio
n Manager\Memory Management]
"SecondLevelDataCache"=dword:00000200
Regards,
Rikki
The default value of SecondLevelDataCache (SLDC) is zero.
Zero means that NT and W2K are supposed to try to retrieve
the actual L2 cache size from the HAL when Windows starts.
There is no advantage to specifying a non-zero value for
SLDC unless you have reason to suspect that Windows is not
successfully getting the L2 cache size from the HAL.
I have seen three recent situations where the HAL did *not*
return the correct L2 cache size and hence the correct value
need to be put into the SLDC reg key:
1.) P4 Extreme Edition processors. Sometimes a BIOS update
fixes the cache recognition problem, but other times you
need to set SLDC.
2.) Xeons with L3 cache. "SecondLevelDataCache" is an outdated
name for this reg key. It would be more accurate to call
is "LastLevelDataCache" because it should store the size of
the last level of cache as you go from the CPU to the RAM.
Sometimes Windows will use the L2 cache size because the HAL is
ignoring the L3 cache. Again, sometimes a BIOS update will
solve the problem, but other times you will need to set SLDC to
a non-zero value.
3.) Barton core AthlonXP's on older motherboards. If the motherboard
cannot provide the native 333 MHz FSB for a Barton (so that you
have to underclock it with a 266 MHz FSB), often there is no BIOS
update so that the system will correctly identify the processor
and the cache size. If your motherboard's FSB tops out at 200 or
266 MHz, then play it safe and set the SLDC to 512 KB.
I would assume there are similar situations with newer Durons on
older motherboards, but I have not personally run into this yet.
Generally speaking, if the POST returns the correct name, speed,
and cache sizes for the processor, then the Windows will get the
correct cache sizes from the HAL.
If you are not sure whether or not your system is using the full
L2 cache, here's lots of utilities:
http://www.benchmarkhq.ru/english.html?/be_memory.html