I'm not sure that I see that article as indicating that voltage controls fan speed.
Fan speed can influence when the temperature target is hit, but it's not going to spool up just because voltages change.
Voltage can govern the highest stable clocks that can be achieved, with the caveat that at any given clock speed higher voltage equals higher power consumption.
If the fan's speed is maxed out and the temperature target is hit, neither clock or voltage increases will provide a benefit. The fan was manually set to 100% to push this scenario as far out as possible.
If the temperature target is not hit, but the clock and voltage curve hits the power target, then the fan can do nothing.
The overclocking attempt appears to be mostly capped by stability, although the more uniform clock graph for the overclocking attempt may mean another target is being hit. It might be the temperature target in the early part, but power limits might be contributing to some of the behavior that later doesn't match the temperature readings.
No it is part of the whole package, voltage is linked to the frequency in some way as temperature (but the temp is never above 65 in that link I gave) which is why it drops IMO (voltage profile-algorithm with frequency).
That example I provided before is with the fan set to 100%, so I am showing it is more likely your seeing the voltage-frequency profiling of Boost3 in action as it is nowhere near as bad as the one where they showed it with a temp of 82degrees.
You can set individual voltage to clock speed.
Quoting TPU who also done a nice study showing influences to boost.
Currently, there are 80 voltage levels and you can set an individual OC frequency for each, which would make manually OCing this card extremely time intensive. That's why NVIDIA is recommending that board partners implement some sort of OC Stability scanning tool that will create a profile for you.
http://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_1080/29.html
So to me the issue at moment probably comes back to the voltage profile when it peaks, as HardOCP shows similar kind of frequency control when temperature is stable at 65 - see chart in post 1014.
Just to add, TPU had to stop the fan to get a trend above 82 degrees.
Anyway Boost3 is more complex than what has been implemented in the past for either NVIDIA or AMD, so I see it still requiring fine tuning and probably how it profiles voltage-temp-offset to frequency, which is not helped with NVIDIA being too soft with the fan profiling and so it hits 82 too easily if not modified.
Note it is rather dynamic, which means we can see different behaviour/trends influencing it hitting the ceiling in terms of voltage-clock per game and also per "scene" in a game.
As an example look how it can vary by a large amount per game in the following chart at gameshardware, 10mins warmup:
http://www.pcgameshardware.de/Nvidi...5598/Specials/Benchmark-Test-Video-1195464/2/
Again please note this does not necessarily reflect the maximum OC one can get on the FE design, but how it can vary by a wide margin per game and the dynamic boost hitting the ceiling at points in a game.
Cheers
Edit: to summarise:
In the past, overclocking worked by directly selecting the clock speed you wanted. With Boost, this changed to defining a fixed offset that is applied to any frequency that Boost picks.
On Boost 3.0, this has changed again, giving you much finer control since you can now individually select the clock offset that is applied at any given voltage level.