# Will CPU stock clock speeds ever exceed 4.0 GHz?

1. Oct 16, 2008

### The_Absolute

The fastest stock clock speed I have ever seen on a CPU the is currently available to the public is the Intel Core 2 Quad 4.0 GHz. (it may be overclocked) For the past few years, clocks on CPU's never seemed to get substantially higher. Is there some kind of thermal limit to how fast you can run electricity through a circuit without it melting/catching fire? They seemed to just add more CPU cores on one die working in tandem. I remember when the Pentium 4 was released, which was solely based on high clock speeds.

I read something on the internet recently about a dual, quad-core CPU computer (eight cores) with each core running at 6.0 GHz. (48.0 GHz) I know that if you tried to overclock a pentium 4 to 6.0 GHz, it would immediately melt and/or catch fire, even with liquid nitrogen cooling it. I'm not an electrical engineer, nor a computer scientist. But I was wondering if maybe in a five years or so we will see 8-16-32+ CPU core systems with each core running at maybe 6.0-12.0 GHz.

2. Oct 16, 2008

### mgb_phys

Yes the problem is mostly thermal. Power in a switching transistor is roughly frequency^2, so going from 4->6GHz is 225% as much power to remove. The problem is made worse with the smaller die rules needed to get more features on a chip, smaller features suffer from thermal damage more easily (thermal migration of dopeants, changes in crystal structure etc)

You can run at high speeds but you have to do a much better job of cooling to get the extra heat out and it's more difficult to get the required amount of power in. Multiple cores, more efficent processor instructions and larger caches are generally a better value for money way of improving performance.

Another possibility is asychronous designs where instead of every transistor running at the full clock frequency the different parts run at different speeds only clocking when they have work to do and going idle while waiting for the results from another part. This is used in some simple lower power embedded designs but is tricky for a full PC type CPU.

Last edited: Oct 16, 2008
3. Oct 16, 2008

### Redbelly98

Staff Emeritus
I've wondered about this myself. It's like Moore's law just hit a wall a few years ago, as far as PC processor speed is concerned.

4. Oct 16, 2008

### Greg Bernhardt

Gaming has always moved the industry. In gaming your graphics card is much more important than your CPU. So most of the advancements are in graphics cards.

5. Oct 16, 2008

### mgb_phys

Strictly speaking Moore's law was that the most cost effective number of transistors to fit on a single CPU would increase expoentially - that's still true.
It didn't say anything about clock speeds or performance.