2 Replies Latest reply on Sep 5, 2011 11:35 AM by Khenglish

    setting MSR 0x1AD (turbo ratio limits) has no effect on Sandy Bridge

    Khenglish

      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?wapkw=software%20developer%27s%20manual 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.

       

      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?