here are the read outs (-X -0) for the MSRs:
0x000000CE -> 00080C10F0011C00
0x00000194 -> 0000000000090000
0x000001AD -> 0000000024242526
I'd say the issue is because of how I determine the overclocking headroom that the CPU is capable of. On my CPUs, it happens that the number of OC bins is the same as the number of steps between the base frequency ratio and the maximum turbo ratio. I imagine this isn't the case for other CPUs (which I do not currently have any of nearby) and would explain why the gains aren't as high as expected.
From what I've heard about Ivy Bridge Mobile CPUs it depends on the TDP (I don't know about the Sandy Bridge or ULV models):
CPUs with 35W TDP should just work as you described.
CPUs with 45W TDP can be "overclocked" by up to 400MHz on top of their maximum turbo ratio. In the case of my i7-3840QM it should reach around 4,2 GHz (without taking additional voltage into consideration).
CPUs with 55W TDP (i.e. the extreme edition "XM") have a unlocked multiplier and may be considered as the equivalent to the "K" CPUs on the desktop.
In its current state, my patch seems to achieve that :P
It certainly does ;) I find it curious though that intel_pstate and acpi-cpufreq exhibit different behaviors in terms of maximum frequency.