Back to the Mac – Part I

The time had finally arrived. Anticipation for the event was at fever pitch. And more than anything, I was ready to enter a new era of personal computing…

The delivery of the future of my creative computing endeavors marked a milestone. It was laid upon our front porch by the FedEx Delivery person with the significance of the final spike driven into the First Transcontinental Railroad. There was no mistaking it – this was an historic moment.

OK, back to reality. I got a new 5K iMac and have been looking forward to it for some time. It is not an inexpensive computer, but thanks to its refurbished status and relative age (a late 2015 model, although currently the latest and greatest from Apple) it didn’t break the bank.

My goal with getting an actual Mac instead of building a Hackintosh was to reduce the inconvenience and anxiety of a custom-built machine with the peace of mind that my computer would be fully supported by Apple for years to come. And although it’s been less than 48 hours with the new machine, I am already enjoying the difference tremendously.

I plan to blog more about my time using the device in the future beyond just the initial impressions, but for this post (and the following) I want to focus on the rationale for my selection in terms of the hardware. But an important caveat to my discussion is this: Apple is rumored to be on the verge of releasing a new iteration of the iMac (having been over a year since the last update). I hope to avoid buyer’s remorse, but there will always be a newer model coming ‘soon.’

So, my justification for purchasing this refurbished iMac must compete with the unknown variable of what’s next on Apple’s product road-map for the iMac. It’s a trade-off for taking the known over the potential benefits of the unknown. But as with much in the technology world, price is critically important.

So enough with the prologue, and onto the specs! (For the real geeks, here’s the nitty gritty spec list).

Apple 27-inch Retina 5K iMac

  • Intel 3.3GHz (3.9 GHz Turbo) Quad-Core i5 CPU
  • 8GB DDR3
  • 128GB SSD + 2.0TB 7200RPM HDD (Fusion Drive)
  • AMD Radeon R9 M395 with 2GB VRAM
  • USB 3.0 and Thunderbolt 2
  • 802.11ac Wireless, Bluetooth 4.0

Processor (CPU)

At first blush, it’s a reasonable machine in terms of specs. The CPU was a bit of a compromise (in an ideal world an i7-6700k clocked at 4.0GHz would have been my first choice), but otherwise a fine quad-core choice for CPU-heavy tasks. It’s much better than many Macs wielding only dual cores, and has the thermal headroom to run full-tilt with video encoding tasks that would be thermally limited on some smaller form-factor devices (e.g. laptops). And in a recent revelation (for me) that challenges the marketing appeal of an i7 being better than an i5 for heavily threaded workloads (such as video encoding) there’s this from Anandtech comparing the (newest generation) Core i5 and i7 flagships parts from Intel:

Both the HandBrake tests essentially mirror what we saw in [Cinebench]15 – the Core i5-7600K is there or thereabouts when frequency is the main factor, and when we stick a register-heavy threaded situation in the path, the effect from not having hyper-threading compared to the Core i7-7700K is relatively muted – in this case the i7 is only +20% performance over the i5, despite costing nearly 50% more. Our Hybrid test is somewhat similar to the HandBrake HQ test, showing the fact that heavy threads reduce the efficacy of hyper-threads. –

Translation – you don’t get as much bang for your buck from the more expensive i7 model with hyper-threading as you’d think.  The i5 can be the sweet spot even for some heavily-threaded use cases depending on the workload.

Graphics Card (GPU)

Despite AMD’s new Polaris architecture and accompanying GPUs being launched this past summer, the current iMac has a GPU architecture based on a 28nm process (Pitcairn/Tonga/Fiji) technology. It therefore doesn’t benefit from either the architectural changes with Polaris and also lacks the newest generation’s cooler-running 14nm process technology. However, the importance of the GPU in a Mac (not used for gaming in my case) really comes down to a few key points:

  • User Interface (UI) responsiveness in macOS
  • Ability to effectively drive a high-resolution (5K) display
  • External monitor support (not applicable in my use-case)
  • Thermal performance (GPUs tend to generate the most heat of any part of the computer)
  • Application support / utilization (GPU acceleration)

For comparison, the GPU in the model I have is 2nd from the top in terms of ability.  The top end version (AMD Radeon R9 M395X graphics processor with 4 GB VRAM) is a pricey upgrade for only the most demanding application needs (and frankly isn’t a great gaming GPU either). The extra RAM could be useful in games or external monitor support (more frame-buffer to fill), but the one I have should be sufficient for my modest video / podcast editing needs.

The UI for macOS will run well in the upgraded GPU I have (vs. the base model M380 or M390) and will be plenty for driving just the one 5K display (no external monitors). Thermal performance for the M300 series is much improved vs. last generation’s M200 series (which saw thermal throttling limit performance in GPU-intensive tasks) despite being on the same 28nm process. And really, who likes to hear computer cooling fans spinning at high RPM? While I won’t get the full benefits of an M395X with 4GB VRAM for the applications that can use it, the scenarios that would optimally use those resources (heavy effects and filters in Final Cut Pro X or Photoshop) aren’t really anything I plan to do.

In Part II, I’ll wrap up my thoughts on the memory, storage, screen, miscellaneous items, and conclusion. To be continued…

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