Famous 2012 Mac Pro buyer Marco Arment has put together a list of probable Mac Pro CPU options. Marco ends his piece with recommending the 6 core as a probably sweet spot of cost, cores, and turbo. He’s probably right about that. But let’s pretend cost was no object (or Apple takes higher margins on the low end rather than the high end or some other crazy nonsense). If we’re just talking about getting the job done using only one processor, what kinds of tasks are likely to be hurt by having too many cores and a weaker turbo boost?
In my life: none. Even the most out of date things that render I still occasionally use (Final Cut Pro 7, other 32bit renderers) comfortably max out 4 threads when rendering. Everything else (Final Cut Pro X, Premiere CC, other 64bit renderers) all use at least 8 threads, which is all I can confirm on my dual quad 2.8Ghz 2008 Mac Pro and a Quad i7 retina MacBook Pro.
The most recent thing I did that took a while (20 minutes) that couldn’t’ve been improved by throwing more cores at it happened to also not be something that could have been made faster by a higher turbo, since it was only using about 10% of the CPU the whole time. It was a command line php script (that’s right) that took 2GBs of IIS log files and dumped them into a mysql table so I could get some analytics out of it. The bottlenecks were mainly disk IO (even though the logs were on my local SSD) and the minimum time for a SQL INSERT to execute (even with a persistent connection).
Another reason to prefer more cores, even if slower, is because there’s a lot of crappy software out there that you can’t get out of using. For whatever reason, Adobe updaters sometimes block and eat up 100% of a single [processor] thread. The more cores you have, the less collateral damage to processes that deserve the CPU. (If Adobe’s never going to get on the App Store train, they could at least use standard Installer.app .pkgs… that would be nice…).
On that note, giving virtual machines less than 100% of your physical cores to work with can help prevent them from locking up your entire system. Because I’m working on developing an Intranet right now, I have multiple Virtual Machines with various versions of Windows and IE constantly running, all quarantined to one or two cores and maybe a gig of RAM. The Intranet is also hosted by yet another local virtual machine. Although this causes my retina MacBook Pro to reach 160°F if I don’t use SMCfancontrol and/or a supplemental USB fan, performance never suffers except inside the virtual machines themselves as I only have so much RAM given to each of them. RAM is actually the lower ceiling on how many VMs I can run at a time.
When I’m not rendering anything, even with all those virtual machines sitting there serving and receiving http requests my CPUs are generally at least 90% idle. Whenever I do anything CPU intensive however, it likely is using as many cores as possible, so it’s only going to get a 133MHz Turbo per core, in which case, more is better. As I’m only used to maxing out 8 threads, I might be able to squeak by with the quad core model as long as I can affordably stuff enough RAM into it. Currently, Crucial is assuming this 16GBx2 kit will work and costs $439.99, making it $879.98 for the full 64GB, which IMO is a more worthwhile upgrade than going from 4 to 6 cores for the same price (though I’m sure it’ll be $2000 in Apple RAM prices).
Interestingly, going from 4 to 6 cores also gets you a GPU bump. If you dream of using the maximum of three 4K displays and still having enough VRAM available to do more than render the UI then going with the 6 core just for the presumably cost effective GPU boost is a no brainer.
This is a long way of saying it, but, as expected, Apple has provided a comparably “useless” entry level Mac Pro alongside one that’s much more cost effective, but probably still needs some BTO options. Now we wait to see how much those options actually cost piecemeal. I still want 8 cores because I like doubling things for updates, and my 2008 Mac Pro has 2 single threaded quad core cpus (8 threads), so an 8 core hyper threaded CPU would be 16 threads. And there’s no question I need ALL the RAM you can put in it, especially while I’m virtualizing my Sharepoint development servers on it.
Whatever the cost though, if you need the new Mac Pro to do your job, and you’re your own boss, don’t forget that development hardware is tax deductible, and maybe even eligible to be tax free in your state.