Reply to post: Re: Too many cores

Re: Too many cores

not just heat, but the laws of physics, distance being one of them. The physical distance of the wiring between one part of the CPU and another part, or between the CPU+socket and the associated bus [like memory], limits how fast it can possibly go. At ~3Ghz, that distance is (for all practical purposes) less than 1 inch. Keep in mind you need time to send a signal out and get something back, so you double the distance, then factor in settling and response logic times and whatnot and there ya go. If you're lucky you might get away with a longer distance. But the wavelength of a 3Ghz signal is about 10cm. At that distance, an entire clock cycle will have passed before a signal gets from the start to the end of the wire. So the best practical signal length is about 1/4 of that, accounting for logic time on each end, plus some settling time for a pulsed signal. That applies to anything running at 3Ghz. And higher frequencies, of course, are even SHORTER.

The current solution: have a wider bus, more cores, and more levels of cache. Make the cores able to predict branches and hyper-thread and super-scale and do other things to limit "logic time". Otherwise, Mr. Physics makes things impossible.

Heat also being a factor if you reduce distance too much to allow for higher speeds, since with less silicon to transfer this heat to a heat sink of any kind, you could end up with 'hotter localized hot spots' which create entropy and allow "other bad things" to happen, eventually damaging the CPU and rendering it useless... yeah Mr. Physics again.

Then if you reduce voltage even more, you run into the limits of silicon-based [or germanium, or anything else for that matter] materials to act like logic gates, and switching logic levels become less tolerant and settling times may be longer and currents might have to be THAT much higher [rendering the drop in voltage less effective on overall power consumption].

And "idle cores" are more likely the fault of programmers not writing multi-core algorithms, Windows background processes notwithstanding [they're "scampering" instead of "running", i.e. unproductive motion, as far as I'm concerned, so I'd rather have idle cpu cores instead of "doing that"].