Tracking GHz isn't an accurate way to measure performance. Take a look at this table, which looks at Instructions Per Second for a number of different processors/devices:

https://en.wikipedia.org/wiki/Instructions_per_second#Timeli...

To see an example of why GHz isn't an accurate way to look at performance, compare these two:

Pentium 4 Extreme Edition - 9,726 MIPS at 3.2 GHz

Intel Core i7 5960X - 238,310 MIPS at 3.0 GHz

That said, it is possible to have CPUs that exceed 4GHz. Heat is the issue you need to overcome.

Here's an Intel's Core i7-4770K, overclocked to 8GHz:

http://www.tomshardware.com/news/Intel-Haswell-Overclock-i7-...

Thanks a lot.

Comparing your Intel Core i7 5960X with the old 2004 Pentium 4, single thread performance:

  Intel Core i7-4790K @ 4.00GHz  ... 2529 
  Intel Pentium G3258 @ 3.20GHz  ... 2172
  Intel Core i7-5960X @ 3.00GHz  ... 1991
  Intel Pentium 4 @ 3.80GHz      ...  824 
  Intel Atom 230 @ 1.60GHz       ...  238 

https://www.cpubenchmark.net/singleThread.html

Vector processors like the Cray-2 are very awesome and had huge amounts of main memory. We will see nVidia does with their GPUs and AMD does with their APUs that works great already in PS4/XB1.

(MIPS and GFLOPS measurements depend on the benchmark implementation and the used language/compiler/etc.; and they show unrealistic PEAK results, rather than real world performance) LINPACK benchmarks (Fortran based) is better than MIPS AND GFLOPS too, "The performance measured by the LINPACK benchmark consists of the number of 64-bit floating-point operations, generally additions and multiplications, a computer can perform per second, also known as FLOPS. However, a computer's performance when running actual applications is likely to be far behind the maximal performance it achieves running the appropriate LINPACK benchmark" https://en.wikipedia.org/wiki/LINPACK_benchmarks

Or maybe Intel really has hit a thermal limit, rather than hatching a conspiracy against consumers?

(Not saying 10+GHz is necessarily impossible, just that it's more likely hitting it is hard than Intel doesn't want to innovate there for some reason.)

AMD sells CPUs with 4.2+ GHz that can be easily overclocked (like Intel CPUs from 15+ years ago). We are now at 12nm whereas we had >90nm years ago. Increasing the clock speed is certainly possible, but always a tradeoff. We can always put the CPU in a specific oil like the Cray2. If x86/64 is the limiting factor, they could release an incompatible CPU architecture (like the failed Itanium or like ARM). A lot of the die space on current CPUs is internal memory (L1, L2). It's pretty easy to draw the 'conspiracy' card.

AMD's CPUs do many fewer instructions per cycle as Haswell (in some cases half as many), not to mention Skylake. You can't really compare GHz between them.

And releasing a new architecture is not exactly feasible if they want to stay in the server, workstation, and desktop markets. That idea behind Itanium actually was to get faster by dropping x86_64, and we see how poorly it worked out.

I don't think it's due to a lack of competitors that we don't have faster clock speeds but because increasing the clock speed causes the CPU to get too hot, and its difficult to actually get better performance that way. At least it's something along those lines according to several of my previous Electrical Engineering professors.