Hi Geoff On Sun, 16 Jun 2013 20:49:26 +1000 you wrote: I can't provide much in the way of scientific evidence; there are others who know far more about the technical realities of this - and push their machines much harder - than I do. Personally, I have always run with the idea that so long as one has N independent processes whose links to other processes are limited to the consumption or production of streams, then one could theoretically max out N CPU cores. However in most practical cases involving audio and video one is running the streams at real world speed, and this obviously limits the extent that each process requires a CPU. The only time a single process would have the chance to max out a single CPU core would be when freewheeling with jack for example, or doing a final render of a video. If one spends most of the time interacting with their AV software, this means that there's no simple answer to the "how many cores are optimal" questions. It depends on the precise mix of software you're running, what each process requires of a CPU core, how much I/O each process instigates, and so on. Another caveat is jackd: my current understanding is that jack2 can better utilise multiple cores, but I'm happy to be corrected on this point by anyone with more knowledge than I (I really haven't looked into this recently because for my current situation it's academic). My system has been based on a first-generation i7 for the last couple of years and I've noticed no major issues. However, in terms of audio work I'm not really pushing the system all that hard during real work (I don't have soft-synths running generally, and the plugins I use tend to be fairly frugal with CPU requirements). This gives me 4 cores with hypertheading and when I've done tests to see what it could handle, an audio-like workload is able to push well above the 400% loading (so the hyperthreading seems to be doing something useful). Having said all that and knowing the sort of work you do, I would probably err on the side of getting as many cores as you can reasonably afford. As time goes on they won't go astray; you'll have the flexibility to experiment with new ways of doing things without being too constrained by the number of cores at your disposal. A final comment is that with the release of Intel's Haswell-based CPUs we are at an interesting point in time. These new cores are certainly a big win for mobile computing due to their lower power consumption for a given performance level. However, whether the increase in outright performance - the primary metric for a desktop - justifies the "new product" premium these will attract for the next 6-12 months remains to be seen, especially since one would also expect some runout discounting on the 4th generation CPUs in the coming months. Regards jonathan