It would be great if there was a 10GHz CPU (single-core), for some special domains.
A hardware startup company that designs a new CPU that interrups the status-quo would be great. (3GHz in 2004, 3.8GHz in 2006, ~4GHz in 2014)
Like in the 1990s 3dfx (GPU) and Cyrix (CPU):
As processor architects are hitting fundamental physical limits when it comes to increasing clock speeds[1], it would probably take a team of world-class engineers, not a few disruption-minded startup founders, to create a 10GHz CPU. Such a chip would have extreme cooling and power demands and wouldn't necessarily perform well.
Cyrix doesn't seem like a great example, as it mostly competed with Intel on its budget chips, if Wikipedia is correct. I suspect the greater amount of low-hanging fruit in processor design made it easier for smaller companies to compete with Intel in the 90s.
[0]: http://arstechnica.com/gadgets/2011/04/ask-ars-whats-the-rel...
[1]: https://www.quora.com/Why-havent-CPU-clock-speeds-increased-....
http://www.reddit.com/r/askscience/comments/ngv50/why_have_c....
We had already complex pipelining superscalar architecture with Pentium Pro and Pentium 4 (Netburst/Prescott). The current Core Architecture has a lot simpler pipelining based on Pentium 3/M. (see http://en.wikipedia.org/wiki/Clock_rate )
I favor a high single-core over a slow many-core CPUs.
Have you ever coded a many-core application that runs on thousands of CPUs? I have done using it using http://en.wikipedia.org/wiki/Cilk , http://en.wikipedia.org/wiki/OpenMP (and CUDA and OpenCL on GPU), as well as traditional using operating system process and threads.
You need new algorithms that work on massive parallel computers. Converting algorithms from serial to massive parallel is possible in many cases, but really hard science work (have done it).
Nevertheless, for a specific domain I would need a really high speed single-core CPU.
A good book about the topic is "Inside the Machine" from ArsTechnica: http://www.amazon.com/Inside-Machine-Introduction-Microproce... ...and various university lectures.
But originally, you said 10 GHz, a record-breaking clock speed, would be advantageous. I replied to say that I doubt that, given the physical limits mentioned in the links I shared above. If what you originally meant was that processors with fewer cores and better raw performance per core is what you need, then I misunderstood.
>Have you ever coded a many-core application that runs on thousands of CPUs?
Nope. I admit you have more experience in that area than I do, but I don't really see why you brought it up.
>Nevertheless, for a specific domain I would need a really high speed single-core CPU.
Out of curiosity, which domain do you have in mind?
Ivan Sutherland has done some work on a new processor architecture called Fleet, which takes this premise and rethinks how we should program from the bottom-up. Instead of instructions performing operations, the programming model becomes one of passing messages between individual units in the processor, and the problems become that of traffic management and routing, which happens to relate to functional programming, the actor model, and data-flow paradigms.
Have a read of "The tyranny of the clock", and other publications by the Asynchronous Research Center:
http://web.cecs.pdx.edu/~mroncken/ARC-2012-is13_TuringCenten...
There's a reason it hasn't happened.
In 2014 we have now the Intel Haswell (14 nm) with 3D tri-gate transistors yet just 3.7 GHz single-core clock rate.
A 10 GHz CPU from Intel would be possible today, we just need dielectric liquid cooling (not water, but pressured Fluorinert) like the http://en.wikipedia.org/wiki/Cray_2 and http://en.wikipedia.org/wiki/Fluorinert
General public cannot buy such equipment, but it does exist.
- size: higher frequency means you need smaller circuits, otherwise the electric impedance works against fast switching. There's a limit to how small we can build chip components right now.
- molecular stability: higher frequency requires higher voltage (to provide the energy), which in turns makes it easier for the metal oxide to degrade over time (this effect is additional to degradation due to heat)
- phase divergence: the digital circuits in our processors are heavily synchronized, and require components to react simultaneously to clock edges. However the propagation of the clock signal across the chip introduces errors in the signal phase. As the frequency increases, phase errors accumulate and cause circuits to "lose synchronization". To avoid this, one must increase the complexity of the clock distribution network greatly, which in turn compounds the effects above (and the heat problem).
All in all the current state of affairs is summarized by a rule of thumb (so-called "Pollack's law"): the speed (instructions/sec) of a single core processor increases with the square root of its complexity.
By this rule, to clock up from 3 to 10GHz would be a 9-fold increase in complexity, for which we don't have the technology ready just yet.
But yes, the speed of light limitation on signal propagation is a major factor in our current limit of 3 to 4 GHz chips.