The solution is nicely outlined in the [H]ard|OCP Forums, where it’s aptly known as the “Benny Hill Effect”. Turns out that the problem has to do with power state management issues and how they affect the read time stamp counter instruction (RDTSC), which is used for timing. I followed the guide, and it fixed my problems.

The games that I noticed the timing issues in were NFS:MW, Rome Total War and GTA San Andreas. This is by no means a complete list of games that are affected by this issue. Some of my own observations and suggestions for fixing the problem:

• I installed the “AMD Dual-Core Optimizer”, but found that while it fixed some of the jerky games, it caused problems such as video distortion in other games
• So, I uninstalled the fix, and strangely, the jerkiness in games remained gone and all previously caused problems were removed as well
• This may have been the result of the “/usepmtimer” switch being added to the “boot.ini” file (This may have been all that was needed)

Regardless, the guide in the [H]ard|OCP Forums is quite extensive, and you should be able to solve any of your dual-core related gameplay issues by reading it.