FiveTech Software tech support forums

Intended for all owners of dual-core processors, AMD Dual-Core Optimizer is a piece of software that allegedly improves gaming
performance by bypassing Windows' API in some specific situations.

This utility helps that software access the RDTSC instruction directly, in order to correct the Time Stamp Counter on separate
cores. It effectively keeps both cores working in parallel and reduces the differing video performance effects, or any other flaws
that relate to timing situations in dual-core or upcoming multicore processors.

AMD Dual-Core Optimizer utility synchronizes Time Stamp Counter (TSC) MSRs on AMD Dual-Core Processors.
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This software installs and operates under the following operating systems
* MicrosoftR WindowsR 2000
* MicrosoftR WindowsR XP
* Microsoft Windows XP Professional x64 Edition
* Microsoft Windows Server 2003 32-bit
* Microsoft Windows Server 2003 64-bit

Computers that are equipped with multiple processors that support processor power management features, such as Advanced
Configuration and Power Interface (ACPI) processor performance states, require Microsoft Windows XP Service Pack 2 (SP2). Additional
updates are available to optimize performance and behavior on computers that are running Windows XP SP2. Without these updates,
computers that are equipped with these power management-capable, mobile, dual-core processors may experience decreased performance
or unexpected behavior.
*Note* This problem also applies to x64-based versions of Microsoft Windows Server 2003.

Microsoft updated hotfix 896296 (http://support.microsoft.com/kb/896256/) in
June 2006 from v3 to v3.1 (possibly to do with AMD AM2 and/or Intel Conroe
support). They seem also to have removed the download and reverted to the
original release policy of making people contact Microsoft support and hand
over their credit card details and their first-born before Microsoft will
deign to consider whether or not they will make it available.

Since one of the things the 896256 hotfix addressed was applications
directly accessing the TSC it may be that hotfix is now redundant with these
two releases. I have yet to test this myself but early indications from
someone who has installed the Dual Core Processor Driver 1.3.2 and the
Dual-Core Optimizer but not the hotfix would indicate this may well be the
case.