Phenom II Tweaker is a utility for modifying the reported CPUID, instruction set's and CPU name, moreover some settings that is useful for optimizing and testing purposes. Reset TSC: The reported TSC in case of AMD Phenoms is always the Performance state 0 detected at boot time. This can be a potential problem for old programs(eg. NFS 2000) and performance testing tools (eg. latency.exe), since modifying the core clock to lower (or higher) frequencies cannot change the reported CPU speed through TSC. If you use for example K10stat for overclock, yo can use the reset TSC function to force the CPU to report the right Clock speed (ie. the configured p0 state you set in k10stat). Warning: Only use this feature if the operating system not using TSC as a timer source!(but PM timer or HPET). You can check this with Timercheck.exe. If QPC freq is equal CPU p0 freq, or in case of win7 cpu p0 freg/1024, the you must change bios or operating system settings, or leave TSC alone. C1E ON/OFF: Early Phenom II-s don't support hardware initiated, only SMI initiated C1E power saving features. If C1E is enabled in the Bios this setting results in 8-10 watts lower power consumption. But it has a price. Namely lower USB and PCI performance. So by temporarily Switching off C1E before copying files through USB, you can improve the speed. Warning! Only use this feature if at program start the program indicates that C1E is ON! (meaning CPU uses SMI initiated C1E). Change Cpu name string: Pstate Indication and modification. Enable/Disable reported specific supported instruction sets. The Phenoms are already well optimized for SSE instruction execution, but some older programs choose the 3dnow! code path if AMD processors detected. This is suboptimal for Phenom's but you can disable legacy code paths, by disabling the reported instruction set. Faking CPUID (mimic Intel): This feature is not a simple one. You can only use this feature if you can boot from a FAT/FAT32 drive to real mode DOS. You can find the necessary files in the vcpuid subfolder. Put CPUID.XAP in root c:\ (fat32), then start TEST_CPU.EXE from pure DOS, TEST_CPU.EXE will load the operating system founds on C:. Then the booting process repeats itself, and with the help of the program you can mimic intel processors. Even Intel compiler nasty CPU detection can be tricked by this method.