I remember my SNB used to go in C7 last time I played with powertop (2~3 years ago).
But I rechecked and not anymore!

I am on Fedora 23, kernel 4.6-RC3, Lenovo X220 core i7-2620M (SNB)

i7z and powertop report the same : I do not get lower than C3 anymore...

Package | Core | CPU 0 CPU 1
| | C0 active 3.3% 4.5%
| | POLL 0.0% 0.6 ms 0.0% 0.3 ms
| | C1E-SNB 1.0% 0.3 ms 0.4% 0.3 ms
C2 (pc2) 1.1% | |
C3 (pc3) 67.1% | C3 (cc3) 85.2% | C3-SNB 92.7% 2.2 ms 91.5% 3.9 ms
C6 (pc6) 0.0% | C6 (cc6) 0.0% | C6-SNB 0.0% 0.0 ms 0.0% 0.0 ms
C7 (pc7) 0.0% | C7 (cc7) 0.0% | C7-SNB 0.0% 0.0 ms 0.0% 0.0 ms

| Core | CPU 2 CPU 3
| | C0 active 3.9% 9.7%
| | POLL 0.0% 0.0 ms 0.0% 0.0 ms
| | C1E-SNB 0.5% 0.4 ms 0.0% 0.1 ms
| |
| C3 (cc3) 77.3% | C3-SNB 91.9% 3.3 ms 84.3% 8.8 ms
| C6 (cc6) 0.0% | C6-SNB 0.0% 0.0 ms 0.0% 0.0 ms
| C7 (cc7) 0.0% | C7-SNB 0.0% 0.0 ms 0.0% 0.0 ms

| GPU |
| |
| Powered On 0.7% |
| RC6 0.0% |
| RC6p 0.0% |
| RC6pp 99.3% |
| |
| |