Thanks to Wolfgang M. Reimer we might have a fix for this issue!
This fix should work with the following processors :
J2850, J1850, J1750, N3510, N2810, N2805, N2910, N3520, N2920, N2820, N2806, N2815, J2900, J1900, J1800, N3530, N2930, N2830, N2807, N3540, N2940, N2840, N2808
I am currently testing out the script on my N3540. No problems so far.
cstateInfo.sh is to verify the script has worked. The "Disabled" Column will show a "1" for disabled states (or you take a look before running the script and after to check whether the offending C6* states have not been used [ie no change in 'time'])
c6off+c7on.sh is the script which will actually disable the C6* states. And enable C7
This will not work if you have booted with any cstate parameters. (remove intel_idle.max_cstate=1)
The script should be run at boot. If it works, make the change permanent by adding it to startup.
If all is well, you should probably also benefit from better power savings than originally.