To force usage of a certain amount of 2nd level cache in KBytes, edit this DWORD registry key:
Note newer processors like the AMD K6-2 and Pentium2 are using set-associative 2nd Level cache and are detected properly. Force setting the second level cache for such CPUs (And newer) will probably do more harm than good.
[HKEY_LOCAL_MACHINE \System \CurrentControlSet \Control \Session Manager \Memory Management]
SecondLevelDataCache=512 (Default AutoDetect - 0)
More Info MS KB183063
More Info MS KB228766