[ Update: On March 19, 2019, Apple released updates to the iMac Pro. The new system features expanded RAM and an updated GPU option. While the new system improves performance, the recommendations in this article remain unchanged. ]
Ever since Apple released the iMac Pro, my email has been clogged with people asking advice on how to configure their system. So, I did some research and here’s what I learned.
This article is designed to help you make more informed decisions when you don’t have an unlimited budget. Also, the iMac Pro is designed for many different markets. In this article, I’m just focusing on digital media.
NOTE: Here are two other configuration articles you may find useful:
If money is no object, buy the top of the line. It will be blindingly fast, it will work great and you’ll have enormous bragging rights.
But, if money IS an object, then you need to make trade-offs, balancing the performance you need with the money you have.
The good news is that you don’t need to buy the top-of-the-line to get a system today that can meet your editing needs for the next several years.
When Apple rebuilt Final Cut to create FCP X, they focused on upgrading its underlying architecture to take advantage of coming advances in hardware. This includes an all-64-bit architecture, optimization for core technologies including Metal, tight integration with both CPU and GPU, and the ability to take advantage of faster i/o – both to the processors and storage.
There are no optimizations in Final Cut, Motion or Compressor that focus specifically on the iMac Pro. Instead, Apple’s media apps take advantage of whatever technology or performance benefits are provided in the hardware.
In other words, there are no new features in FCP X that appear if it is running on an iMac Pro. What does appear is faster performance.
Apple’s website states:
iMac Pro takes Mac performance to a whole new level, even when compared to our fastest quad-core iMac.
NOTE: Keep in mind that Apple reports these performance numbers are based on: “Testing conducted by Apple in November 2017 using pre-production 2.3GHz 18-core Intel Xeon W-based 27-inch iMac Pro systems with 128GB of RAM and pre-production 3.0GHz 10-core Intel Xeon W-based 27-inch iMac Pro systems with 64GB of RAM, both configured with Radeon Pro Vega 64 graphics with 16GB of HBM2.”
In other words, these numbers are based on the high-end 18-core system, which won’t be shipping until next year and, as you’ll see, may be more than you need.
DO YOU REALLY NEED AN IMAC PRO?
Well, “need” is a relative term. If you principally work with SD or HD material, an iMac will be perfectly fine. The performance benefits of the iMac Pro don’t justify the expense.
If you are hobbyist, no, you don’t need an iMac Pro. This is not the same as not wanting one, but you don’t need it.
However, if the bulk of your work involves 4K or greater frame sizes, 360° VR, RAW files, or HDR, the performance benefits of this new system make it worth considering, because the design of the iMac Pro significantly speeds working with larger frame sizes, faster frame rates, more effects, more processor-intensive codecs (such as HEVC).
With that being said, let’s take a look at the specific components to see which ones make the most sense for video editing.
The iMac Pro uses the same display technology as the 5K iMac. So everything you see on a current iMac looks the same on the iMac Pro:
But, while the display of the iMac Pro is the same as an iMac, the display capability of the iMac Pro is greater:
Before the shouting starts, let me say again that if money is no object, buy the top-of-the-line iMac Pro. However, for most of the editing that most of us are doing, we don’t need to buy the top-of-the-line system to get significantly improved editing performance.
The 8-core system is fine for most editing and compression. For example, H.264 compression takes advantage of a hardware encoder which is built into all current Macs. This hardware encoder is independent of CPU cores.
However, there are benefits to more cores, especially when decoding and encoding heavily threaded codecs like ProRes or HEVC. Also, the 10-core system offers a higher Turbo Boost speed of 4.5GHz versus 4.2GHz for the 8-core CPU. This additional speed benefits rendering and exporting.
The 14 and 18 core systems are designed for other applications than video editing. I would invest my money elsewhere in the system because video editors will see greater benefits in upgrading RAM and GPU when using Final Cut Pro on an iMac Pro.
An exception to staying within a 10-core system is that editors using RED RAW media or working with multiple streams of ProRes — for example, multicam work — will see improved performance with higher-core systems.
Larry’s recommendation: 8 cores for general editing. 10 cores for multicam editing and RAW video workflows.
SIDE NOTE: PERFORMANCE VS. HEAT
One of the issues I’ve heard about the current Mac Pro is that it has a problem with heat under heavy load. What I discovered is that, even more than the Mac Pro, the iMac Pro internals are designed specifically to dissipate heat under heavy load.
Outside, the iMac Pro is millimeter for millimeter the same size and shape as a standard 27-inch iMac with Retina 5K display; outside of the space gray color and a few extra vents on the back. But, on the inside, it’s radically different.
One of the key things Apple was able to do is make the system all flash-based; 3 GB/s of fast SSD is pretty darn fast! Switching to all flash allowed Apple to remove the 3.5” hard drive and use that large space for a dual blower design and a massive heatsink and heat pipe architecture.
This delivers 75% more airflow and 80% more thermal capacity, enabling far more CPU and GPU power in the box over a traditional iMac. It is also worth noting that it does all this while still being super quiet (it is an iMac, after all), letting you focus on your work.
In general, editing video tends to use more of the CPU while effects and graphics tend to rely more heavily on the GPU. Increasingly, both FCP X and Premiere rely on the GPU for more and more tasks. Also, the greater the VRAM, the better the GPU performance.
Whether you use Motion, After Effects, Premiere or Final Cut, investing in the best GPU will be a wise choice.
NOTE: While VRAM is important, VRAM is not the only determinant of a superior graphics card. For example, the Vega 64 is significantly faster in addition to the larger amount of VRAM. Also, more VRAM offers benefits when working with large frame sizes, multiple video streams (i.e. multicam), multiple displays, and complex motion graphics.
Larry’s recommendation: Upgrade to the Vega 64 graphics card or better.
UPDATE: It important to note that buying a better GPU does not improve image quality. What it does, instead, is work faster. Specifically, faster rendering and exporting. If time is scarce, an updated GPU will speed effects rendering, exporting and, in some cases, video compression.
The 32 GB default RAM is fine for virtually all editing. If, on the other hand, you run multiple applications at once – say FCP X, Motion, Compressor, Photoshop and a web browser – 64 GB of RAM is better.
While there is value in more RAM beyond 64 GB, you won’t get enough bang for your buck to justify the additional cost.
Larry’s recommendation: 32 GB for people on budgets, with a maximum of 64 GB for serious multi-application users.
UPDATE: The latest updates allow expanding RAM to 256 GB. Cool. But all you really need is 32 – 64 GB.
The iMac Pro ships with a 1 TB SSD. I have’t measured it, but it is probably way past blindingly fast. (Apple says 3 GB/second!) The problem is that most media projects today far exceed 1 TB in storage. You will need an external high-speed, Thunderbolt 3 RAID system for even medium-sized projects.
Larry’s recommendation: Stay with the 1 TB SSD. Spend your money on faster, bigger external storage.
SIDE NOTE: VIDEO COMPRESSION
Unlike video editing, video compression has its own requirements for system resources. While this is worth its own article here are some thoughts.
Both H.264 and HEVC are relatively highly compressed formats. This compression, of course, leads to smaller file sizes, but the resulting compression requires more processing power. With H.264 and HEVC, decoding and most encoding actions are processed via dedicated H.264 hardware within the system.
NOTE: A select set of custom H.264 encodes in Compressor may use the H.264 software encoder, which is threaded across multiple cores.
So while ProRes encoding benefits from faster, higher-core CPUs, H.264 and HEVC are not similarly CPU bound. Also, it’s important to note that video compression often includes other operations including retiming, scaling, and color conversion — all of which use the GPU.
If you are interested in HDR, 8-bit HEVC does, in fact, support HDR. Still, 10-bit encoding is recommended for the highest quality HDR output when using the HEVC codec. The reason this is important is that current Macs only support hardware acceleration of 8-bit HEVC. This makes the iMac Pro about 3x faster in HEVC encoding than an iMac.
For 10-bit encoding, the HEVC software codec is threaded and can therefore take advantage of multiple CPU cores when encoding; more cores means faster video encoding.
WAIT, WHAT ABOUT THE MAC PRO?
First, Apple has announced and reiterated that they are working on a new, modular Mac Pro. However, they haven’t announced specs nor a release date.
The current Mac Pro is getting long in the tooth. In terms of performance, the iMac Pro is a better choice.
That being said, there are still two reasons to consider the existing Mac Pro:
For me, while these benefits are not trivial, the hardware inside the system has not be upgraded in several years. If you are focused on video editing, the existing Mac Pro is not the best current choice.
Here are my two recommendations for an iMac Pro for video editing: a budget version and a “top-of-the-line-for-editors” version. (The mouse and keyboard come standard, I make no recommendations about either of these.)
TOP-of-the-LINE EDITORIAL VERSION
As always, let me know what you think.
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