[simias]

I like to write emulators as a hobby so I definitely feel your pain, but I'm not holding my breath for a significant frequency boost in the near future. A 4GHz CPU means that every cycle light itself only moves about 7.5cm in a vacuum. If you have a fiber optic cable running at 10GHz at any given time you effectively have one bit "stored" in the fiber every 3cm or so.It's frankly insane that we manage to have such technology massed produced and in everybody's pocket nowadays. My "cheap" android phone's CPU runs at 2.2GHz, 2.2 billion cycles per second.

We can probably still increase the frequencies a bit but we definitely seem pretty close to some fundamental limit in our current understanding of physics. The frequency doublings every other year we experienced until the early 2000's are long gone I'm afraid, and they might never come back until we manage to make a breakthrough discovery in fundamental physics.

[madengr]

I think it’s more of a power dissipation issue. The amount of charge, thus current, you are moving in and out of the gate capacitance is proportional to clock frequency. Sine power is I^2*R, then it is proportional to f^2.

Smaller transistors reduce the I, but R goes up with smaller interconnects. The RC time constant also adds delay, probably more so than length.

That being said, 3D stacking won’t help with heat, and dielets won’t help with delay. I rather have 4 cores at 10 GHz than 64 cores at 3 GHz.