found this on daily tech
AMD has silently released a utility that fixes time stamp counter (TSC) issues with dual-core AMD processors such as the Athlon 64 X2 and Opteron. The AMD Dual-Core Optimizer utility is a driver that synchronizes the time stamp counter on both processor cores and improves game compatibility and performance. Time stamp counter issues occur in older games that are incompatible with multithreading and would run too fast or out of sync.
Issues also occur in newer games and applications that have compatibility issues with processor affinity like Need For Speed: Most Wanted. Affinity issues typically required users to bring up the task manager and set the processor affinity manually or performance would suffer dramatically.
The AMD Dual-Core Optimizer utility could possibly be the rumored Reverse Hyper-Threading patch that would improve single thread application and games performance by having dual-core processors show up as a single core processor in applications. AMD has declined to comment on "Reverse Hyper-Threading."
AMDs Dual-Core Optimizer utility version 1.0 is available from AMDs website. The utility release notes shows it as being released on March 22nd, 2006 which is strange as AMD has made no mention of the utility publicly. The utility also installed on Core Duo and Opteron systems.
for those who dont want to read the whole article, some people think it's the rumored reverse hyper threading. it fixes the issues that occur between games that dont fully support dual core CPU's and make then take advantage of both cores, and it even makes game that dont take advantage of both cores, and makes tham do so.
you can download the utility here