Quote Originally Posted by unclewebb View Post
astaris: IA32_PERF_STATUS MSR (address 198H) used to contain information about VID for Core 2 Duo processors but it does not seem to contain VID information for Core i7 CPUs. The one Core i7 that I saw didn't seem to have anything stored in the upper 32 bits of that register. The lower 32 bits have also changed compared to Core 2 Duo.

RT MSR Tool



I think the lowest 5 bits contain the CPU multiplier for Core i7.
0x17 = 23 decimal

That's from a Core i7 940 in Turbo mode which has a multi of 22 + 1 for the Turbo.

This value changes by 1 depending on load and if Turbo mode is being used but it doesn't seem to have any relationship to VID anymore. Core i7 owners can download my tool and test their own CPU. Post a screen shot if you see something other than your multi hiding in there.

Bits [63..16] of this register are listed as Reserved and are not publicly documented by Intel and the bottom 16 bits are not clearly documented by Intel either. The docs only say "Current performance State Value" but it doesn't explain how to interpret those bits. I have a plan B to try and find where VID info has moved to but I don't like my chances at the moment.
Ok, i'm wondering if register IA32_PERF_Control (0X199) changed too, because in the old processors it stored the target vid+fid, so in performance 0 level it should store the default vid of the processor.