INFO: Registry Key to Improve Boot Performance on Some Multiprocessor Systems

If recommended by the original equipment manufacturer, you can set the following registry key to use extended memory manager interface (XMMI) memory zeroing on a Pentium 4 multiprocessor platform. By default, the XMMI zero loop is not used on Pentium 4 multiprocessor systems because of hardware issues that result in a performance degradation when using the XMMI zero loop on many Pentium 4 multiprocessor systems.

Set the following registry key with the value that is indicated:

For this key to work correctly, all the following conditions must exist:

• XMMIZeroingEnable is present
• XMMIZeroingEnable is of type REG_DWORD
• XMMIZeroingEnable does not have a value of 0

Warning Do not use this setting unless specifically recommended by the OEM. Performance improvements will be seen only on some specific machines. The third-party products that are discussed in this article are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.