Really like the way you put this

Your concept is fine, and I like it , but the Maths is slightly inaccurate

It is a bit dubious to say that people can generally overclock CPUs by 10%, 20% or any other number! It helps to be a bit more specific. Many CPU’s do overclock, but many will not (or only very slightly; 3%), either due to the CPU or more likely the limitations of the motherboard (OEM systems especially), or another component (sometimes RAM, GPU, heatsink or even PSU).
From experience I can say that until recently most modern AMD CPUs did not overclock well and were very difficult to work with. With the early Phenom’s for example – I struggled to overclock by 5%. My Phenom II 940 on the other hand was perfectly stable at 110% and I know that if I upped the core voltage I could have clocked it much higher. As it has a GTX260 crunching 24/7 and with stability being key, it now sits natively clocked.

Intel’s dual and quad cores tend to clock better, and more easily! A Q6600 will typically clock from its native 2.4GHz to somewhere between 3GHz and 3.6GHz (on air). That is 125% to 150%, or from another point of view the equivalent of having another 1 or 2 cores
Intels more recent multi-core CPUs (Q9400, Q9450, Q9650,Q8200, i7’s, i5’s and many more) tend to clock slightly better.

Making the Maths Add up:
If you overclock a system by 20% it will not do an additional 20% work, it will actually do a bit more; 25%.
Similarly, a CPU clocked to 125% is actually 33% faster, and will therefore do 33% more work, not 25%.
The point is you just need 3 identical systems clocked to 125% to contribute as much as 4 natively clocked systems!
So your 16threads working 33% faster are doing as much work as 21threads

Regarding my temperatures I tried various applications to check for consistency and I found the values to be consistent to 3, 4 degrees.

So my 950 with cores at 90-95 degrees did show consistently that value. In my bios you get a CPU temp value and not a core per core value. But when you are in the bios you are in idle mode so temps fall.

Anyway, I opened my case to see if something was wrong. And indeed something was wrong. The frame fixture on the mainboard supporting the big CPU cooler with its own fan, had ruptured on one leg. So there was not anymore a full contact between the cooler plate and the CPU.

I changed the frame and the fixtures reinstalled everything and now I get on the overclocked CPU consistent readings at 55-65 degrees like with my other CPU's.