This information doesn't seem to be available on the web anywhere, so I did some measurements. Here they are:
The first column is the CPU core frequency. Most of the frequencies listed are the ones that can be selected by the operating system. The last three frequencies are the ones selected by the chip, based on the number of active cores, when the operating system requests maximum frequency.
The second column gives the core voltage at the specified frequency. These voltages should be taken as approximations for three reasons:
1) The granularity of the measurements is 0.016 volts. A trailing + or - means that I sometimes measured the next higher or lower value. For example, "0.880-" means that some readings were 0.880 and some were 0.0864, so the actual value is probably just above 0.872.
2) The voltages were measured using the Nuvoton NCT 6791D chip on the motherboard, which reads about 1.5% above the actual voltage (at least when measuring the power supply output).
3) These numbers only apply to my chip; Intel may program slightly different numbers into different chips depending on the results of factory testing.
Code:
Ghz volts
0.8 0.768
1.0 0.784
1.2 0.800
1.4 0.816
1.6 0.832
1.8 0.848
2.0 0.880-
2.1 0.880
2.3 0.896
2.5 0.912+
2.7 0.944-
2.9 0.944+
3.1 0.960+
3.3 0.992-
3.5 1.008-
3.7 1.040 (4 cores active)
3.8 1.056+ (3 cores active)
3.9 1.088- (1 or 2 cores active)
The second column gives the core voltage at the specified frequency. These voltages should be taken as approximations for three reasons:
1) The granularity of the measurements is 0.016 volts. A trailing + or - means that I sometimes measured the next higher or lower value. For example, "0.880-" means that some readings were 0.880 and some were 0.0864, so the actual value is probably just above 0.872.
2) The voltages were measured using the Nuvoton NCT 6791D chip on the motherboard, which reads about 1.5% above the actual voltage (at least when measuring the power supply output).
3) These numbers only apply to my chip; Intel may program slightly different numbers into different chips depending on the results of factory testing.