Setting MSR 0x1AD in windows does not change the maximum turbo ratio limit as http://www.intel.com/content/www/us/en/processors/xeon/intel64-ia32-architectures-manual-vol3.html?w... says it should, even if MSR_PLATFORM_INFO bit 28 is high. The processor does not even respond to lowering the turbo ratio limit. This has proven true numerous times on multiple Sandy Bridge based systems, including PCH P67 systems.
It seems that the CPU is not bothering to read the MSR and set itself to the new value. Does anyone have an idea on what must be done to force the CPU to change its maximum turbo ratio limit while the system is in Windows or another OS?
Here are some things I have tried:I have set the turbo ratio limit MSR, then rebooted, but the register would get reset. I have set the MSR, put computer to sleep, and resumed, but the register would be reset. I have booted with turbo disabled, set the MSR, then enabled turbo, but there was no change in the turbo limit.